ASVAB Practice Test

Answer: B
Cylinder volume is V = πr²h = 3.14×3²×10 = 282.6 cubic cm. Using the radius but forgetting to square it, π×3×10 = 94.2 cubic cm, drops the exponent the formula requires. Doubling the radius as if it were a diameter and squaring that instead, π×6²×10 = 1130.4 cubic cm, is four times too large. Leaving out π entirely, 3²×10 = 90 cubic cm, ignores that a circular cross-section is involved at all.

Answer: A
Volume of a rectangular solid is length × width × height: 4 × 3 × 2 = 24 cubic feet. Adding the dimensions gives 9, and 52 is the crate's surface area — a different measure that answers a different question. Volume questions on Mathematics Knowledge stay computational; the skill is pairing the formula to the three-dimensional ask and keeping units cubic.

Answer: C
Greater than 4 means rolling 5 or 6 — two favorable outcomes out of six equally likely, so 2/6 = 1/3. Including 4 itself (three outcomes) produces the 1/2 trap, which is why the strict inequality matters: 'greater than' excludes the boundary, 'at least' includes it. Counting the favorable list explicitly beats reasoning about it abstractly.

Answer: C
With a=2, b=-5, c=-3, the discriminant is b²−4ac = -5² − 4(2)(-3) = 49, and √49 = 7. The quadratic formula gives x = (−b ± √(b²−4ac)) / 2a = (5 ± 7) / 4, which simplifies to x = 3 or x = -1/2. Using +b instead of −b in the numerator gives x = 1/2 or x = -3. Forgetting to take the square root of the discriminant and plugging in 49 directly gives x = 27/2 or x = -11. Dividing by a instead of 2a gives x = 6 or x = -1.

Answer: D
Move every term to one side first: 3x² + 2x - 8 = 0. Then a=3, b=-2, c=-8, so the discriminant is -2²−4(3)(-8) = 100 and √100 = 10. The formula gives x = (2 ± 10) / 6, which is x = 2 or x = -4/3. A sign error on b in the numerator gives x = 4/3 or x = -2. Dividing by a instead of 2a gives x = 4 or x = -8/3. Forgetting to take the square root of the discriminant gives x = 17 or x = -49/3.

Answer: A
When multiplying powers with the same base, add the exponents: 2³×2⁴ = 2^(3+4) = 2^7 = 128. Multiplying the exponents instead of adding them (a rule that only applies to a power raised to another power) gives 4096. Subtracting the exponents, which is the rule for division, gives 2. Doubling the base while keeping one exponent gives 64.

Answer: D
A power raised to a power multiplies the exponents: (2³)² = 2^(3×2) = 2⁶ = 64. Then dividing same-base powers subtracts exponents: 2⁶ ÷ 2² = 2^4 = 16. Adding the exponents in the power-of-a-power step instead of multiplying them gives 8. Adding exponents on the division step instead of subtracting gives 256. Ignoring the division entirely leaves 64, the value of the numerator alone.

Answer: D
A fractional exponent m/n means take the nth root, then raise to the mth power (or in either order): 4^(3/2) = (√4)³ = 2³ = 8. Treating the exponent as an instruction to just multiply the base by the fraction (4×3÷2) gives 6, which ignores what a fractional exponent actually means. Computing 4³ and then dividing by 2 instead of taking the square root gives 32. Forgetting the root step entirely and just computing 4³ gives 64.

Answer: C
The square root symbol asks: what positive number, multiplied by itself, gives 81? Since 9×9=81, √81 = 9. Dividing 81 by 2 instead of finding its root gives 81/2, confusing a root with a division. Leaving the number as 81 means the root was never taken at all. The negative value -9 is also true that (-9)×(-9)=81, but the radical symbol √ always denotes the nonnegative root by convention.

Answer: B
√50 = √(25×2) = 5√2 ≈ 5×1.41 ≈ 7.07, which rounds to 7.1. Simplifying 5√2 but then multiplying the 5 and 2 together instead of keeping √2 as a decimal gives 10.0. Splitting 50 as 25×2 correctly but then dropping the leftover √2 entirely (as if √50=√25) gives 5.0. Truncating 7.071 down to 7.0 instead of rounding it misreads the digit after the tenths place.

Answer: D
Find the largest perfect-square factor of 72: 72 = 36×2, and √36=6, so √72 = 6√2. Pulling out a smaller perfect square instead, like 9×8, gives 3√8, but √8 can still be simplified further, so it is not fully reduced. The same problem happens with 4×18, giving 2√18. Forgetting that √36=6 (not 36 itself) and leaving the whole perfect square under the coefficient gives 36√2.

Answer: A
x² − 16 is a difference of squares, since 16=4², so it factors as (x − 4)(x + 4). Multiplying that out confirms it: the middle terms cancel, leaving x² − 16. A guessed factor pair like (x−8)(x+2) multiplies out to x²+-6x−16, which has an unwanted x-term. Treating it as a perfect-square trinomial, (x−4)² or (x+4)², produces +16 at the end instead of −16, and an x-term that should not be there at all.

Answer: D
Find two numbers that multiply to -12 and add to -1: 4 and -3 work, since 4×-3=-12 and 4+-3=1. That gives (x − 4)(x + 3). Flipping both signs, (x + 4)(x − 3), multiplies to the same product but adds to the wrong sum. Using −3 instead of +3, as in (x − 4)(x − 3), changes both the sum and the product. Using +4 and +3, as in (x + 4)(x + 3), gives the right product's magnitude but the wrong sign pattern throughout.

Answer: C
The greatest common factor includes both the largest shared number and the lowest shared power of x: GCF(12,18)=6 and the lowest power is x², so the full GCF is 6x², giving 6x²(2x + 3). Factoring out only the 6 and leaving the x’s behind, 6(2x³ + 3x²), is still true but not “completely” factored, since x² can still be pulled out. Using a smaller numeric factor like 3 instead of 6, or a lower power of x like x¹ instead of x², leaves a common factor stranded inside the parentheses either way.

Answer: D
Subtract 7 from both sides: x < 15 − 7 = 8. Subtracting a positive number from both sides never flips the inequality, so the direction stays “less than.” Adding 7 instead of subtracting it gives x < 22. Flipping the inequality to “greater than” when nothing was multiplied or divided by a negative gives x > 8, which is a different rule applied at the wrong time. Computing 7 − 15 instead of 15 − 7 gives x < -8.

Answer: B
Add 4 to both sides: 3x ≤ 15, then divide by 3 (a positive number, so the inequality direction is unchanged): x ≤ 5. Subtracting 4 again instead of adding it gives 3x ≤ 7, or x ≤ 7/3. Adding 4 correctly but forgetting to divide by 3 leaves x ≤ 15. Flipping the inequality even though only division by a positive number occurred gives x ≥ 5.

Answer: A
Subtract 9 from both sides: -4x > 12. Now divide by -4, a negative number — and whenever you multiply or divide an inequality by a negative number, the direction must flip: x < -3. The most common error is forgetting to flip the sign after dividing by a negative, which gives x > -3, the wrong direction with the right number. Adding 9 instead of subtracting it changes the numerator entirely, producing -15/2 with either direction.

Answer: D
Convert both fractions to a common denominator of 12: 3/4 = 9/12 and 1/6 = 2/12, so the sum is 11/12. Adding the numerators and denominators straight across without finding a common denominator gives 2/5, which is never valid for addition. Multiplying across instead of adding gives 1/8. Finding the right common denominator but subtracting the numerators by mistake gives 7/12.

Answer: B
First convert the mixed number to an improper fraction: 2 1/3 = 7/3. Then multiply straight across: (7×3)/(3×5) = 7/5. Multiplying the whole number and the fraction 3/5 separately, then adding the leftover 1/3 back in unmultiplied, gives 23/15. Dropping the 1/3 part of the mixed number entirely gives 6/5. Multiplying the wrong pair of numbers across gives 35/9.

Answer: A
Dividing 5 by 7 gives 0.714285..., which rounds to 0.71 because the digit after the hundredths place (4) rounds down. Confusing this with the more familiar fraction 3/4 = 0.75 is a common recall error, but 3/4 and 5/7 are not equal. Rounding up to 0.72 misapplies the rounding rule when the next digit is below 5. Flipping the fraction and computing 7/5 instead gives 1.40, a completely different value.

Answer: D
A prime number has exactly two factors: 1 and itself. Testing small divisors, 51, 57, and 87 are all divisible by 3 (51=3×17, 57=3×19, 87=3×29), so none of them is prime. Checking 61 against every whole number up to its square root (2, 3, 5, 7) shows no even division, confirming 61 is prime. A quick way to eliminate options first is checking divisibility by 3, which catches most composite three-digit-adjacent numbers on the ASVAB.

Answer: A
36 = 2²×3² and 48 = 2⁴×3. The GCF takes the lowest power of each shared prime factor: 2²×3 = 12. Computing the least common multiple instead of the greatest common factor gives 144, the LCM of 36 and 48. 6 is a common factor of both numbers, but it is not the greatest one — it misses the shared factor of 2 that 12 includes. 4 only captures the shared power of 2 and leaves out the shared factor of 3.

Answer: A
The multiples of 8 are 8,16,24...and the multiples of 12 are 12,24...; the smallest one they share is 24. Computing the greatest common factor instead of the least common multiple gives 4. Multiplying 8×12 directly overcounts the shared factors when the numbers are not coprime, giving 96 instead of 24. 48 is indeed a common multiple of both numbers, but it is twice as large as the least one.

Answer: C
Since 2 is even, 3n + 2 is odd exactly when 3n is odd. Multiplying an odd number (3) by n only produces an odd result when n itself is odd (odd × odd = odd; odd × even = even), so n must be odd. Concluding n must be even reverses this relationship entirely. Requiring n to be a multiple of 3 confuses the coefficient in the expression with a property of n, which the parity argument never establishes. Requiring n to be prime introduces a condition that has no connection to the odd/even reasoning at all.

Answer: D
Slope is rise over run: (y₂−y₁)/(x₂−x₁) = (11−3)/(6−2) = 8/4 = 2. Flipping the fraction to run over rise gives 1/2. Subtracting the y-values in the wrong order while keeping the x-values in the original order gives -2, a sign error. Adding the coordinates instead of subtracting them — treating slope like an average — gives 7/4, which is not how slope is defined at all.

Answer: A
The midpoint averages each coordinate separately: ((-4+2)/2, (6+-2)/2) = (-1, 2). Subtracting the coordinates instead of adding them before dividing by 2 gives (-3, 4). Adding the coordinates correctly but forgetting to divide by 2 gives (-2, 4), which is the sum, not the average. Swapping which average becomes the x-coordinate and which becomes the y-coordinate gives (2, -1).

Answer: A
The distance formula is the Pythagorean theorem applied to the horizontal and vertical legs: √((x₂−x₁)²+(y₂−y₁)²) = √((3)²+(4)²) = √25 = 5. Computing 3²+4²=25 correctly but forgetting to take the final square root leaves 25, the squared distance rather than the distance itself. Simply adding the two leg lengths without squaring or rooting at all gives 7. Taking the square root of the leg lengths before squaring them (√(3+4)) gives 2.65, skipping the squaring step entirely.

Answer: B
Using y = mx + b with the known point: 1 = 3(2) + b, so 1 = 6 + b, and b = 1 − 6 = -5. Adding 6 instead of subtracting it when isolating b gives b = 7. Forgetting to multiply the slope by the x-coordinate and treating the equation as 1 = 3 + b gives b = -2. Subtracting the slope and the x-coordinate separately, as raw numbers rather than as the product mx, gives b = -4.

Answer: A
The interior angles of any triangle sum to 180°, so the third angle is 180° − 48° − 77° = 55°. Simply adding the two given angles without subtracting from 180° gives 125°, which is not an angle measure derived from the triangle rule at all. Using 360°, the angle sum for a quadrilateral, instead of 180° gives 235°. Subtracting only one of the two given angles from 180° and forgetting the other gives 132°.

Answer: A
Area uses the radius, not the diameter: radius = 14÷2 = 7 in, so area = πr² = 3.14×7² = 153.9 sq in. Using the diameter itself as the radius gives π×14² = 615.4 sq in, four times too large. Using the circumference formula πd = 44.0 in mistakes a perimeter-type measurement for an area. Using the correct radius but forgetting to square it, π×7 = 22.0, drops the exponent the area formula requires.

Answer: D
Perimeter is the distance around the shape: P = 2(l + w) = 2(9 + 4) = 26 m. Multiplying length by width instead of adding them gives the area, 36 sq m, a different measurement entirely and the wrong units for this question. Adding the length and width but forgetting to double the sum (missing that all four sides count) gives 13 m. Doubling only the length and adding the width once, 22 m, misapplies the formula to just one pair of sides.

Answer: A
The Pythagorean theorem gives c² = a² + b² = 9² + 12² = 225, so c = √225 = 15. Computing 225 correctly but forgetting to take the final square root leaves 225, the value of c² rather than c. Simply adding the two legs without squaring or rooting at all gives 21. Subtracting the squares instead of adding them, √(12²−9²), gives 7.94, which would only apply if solving for a leg using the hypotenuse, not the other way around.

Answer: D
Add 9 to both sides to get x² = 9, then take the square root of both sides. Because a negative number squared is also positive, both x = 3 and x = -3 solve the equation. The most common slip is forgetting to take the square root at all and reporting 9 and -9, the squared values themselves. Reporting only the positive root misses that -3 squared also equals 9.

Answer: C
Look for two numbers that multiply to -10 and add to 3: 2 and -5 work, since 2×-5=-10 and 2+-5=3. That factors the equation as (x-2)(x+5) = 0, giving x = -5 or x = 2. Flipping the sign of one or both roots is the most common factoring mistake, since it is easy to mismatch which factor should be added and which subtracted.

Answer: A
Distribute the 3 across both terms: 6x − 12, then combine with 5x to get 11x − 12. Forgetting to multiply the −4 by 3 leaves −4 (the second choice); adding 5 + 3 + 2x-coefficients wrongly gives 16x. Distribution errors on the second term inside parentheses are the dominant algebra slip on Mathematics Knowledge — the negative term always gets the multiplier too.

Answer: C
Evaluate each power: 3² = 9 and 2³ = 8, so the sum is 17. The 12 distractor multiplies base by exponent (3×2 + 2×3), the most common exponent misconception, and 36 multiplies the two powers instead of adding. Exponents mean repeated multiplication of the base — writing out 3×3 and 2×2×2 takes five seconds and eliminates the error class entirely.

Answer: B
Divide both sides by 4 first: x − 3 = 5, then add 3: x = 8. Distributing first (4x − 12 = 20 → 4x = 32 → x = 8) lands in the same place. The x = 5 trap stops after the division without restoring the subtracted 3. Mathematics Knowledge rewards picking whichever route has fewer steps and checking by substitution: 4(8 − 3) = 20 confirms it.

Answer: A
Start with the actual fuel: 3/4 of 48 = 36 gallons, then subtract the trip's 15: 36 − 15 = 21 gallons. The 33 distractor subtracts from full capacity, skipping the fraction step entirely. Multi-step word problems on the ASVAB chain a fraction operation to an arithmetic one, and writing the intermediate value down prevents the skipped-step errors that timed pressure invites.

Answer: A
Time equals distance divided by rate: 180 ÷ 45 = 4 hours. Arithmetic Reasoning leans heavily on the distance-rate-time triangle, and the fastest check is estimation — at 45 mph you cover 90 miles in 2 hours, so 180 miles must take twice that. Misreading which quantity is asked (time versus distance) causes more misses than the arithmetic itself.

Answer: D
Simple interest is principal × rate × time: 2000 × 0.05 × 3 = $300. One year earns $100, and three years earn three times that. The $2,300 answer is the final balance rather than the interest — reread whether the question asks for interest earned or total amount, because the ASVAB plants both among the choices on nearly every interest problem.

Answer: A
Fencing follows the perimeter: 2 × (30 + 20) = 100 feet. The 600 answer is the area in square feet — the enclosure question's standard bait — and 50 adds the two dimensions once instead of twice. Translate the physical ask into the right measure first: fencing, borders, and trim are perimeter; paint, carpet, and sod are area.

Answer: A
Average speed is total distance over total time: 210 ÷ 3.5 = 60 mph. Dividing by 3 instead of 3.5 gives the 70 trap. A clean mental route: 3.5 hours at 60 mph is 180 + 30 = 210 miles, confirming the answer. Decimal-hour division trips more candidates than the concept, so converting 3.5 to 7/2 and multiplying by 2/7 is often faster.

Answer: A
Average equals the total miles divided by the number of days: 250 ÷ 5 = 50 miles. Dividing by 4 days instead of 5, forgetting one day, gives 62.50. Dividing by 6 days, one too many, gives 41.67. Reporting the single highest day's mileage, 60, instead of computing an average across all five days ignores the other four days completely.

Answer: A
The drop is the difference: 7 − (−9) = 7 + 9 = 16 degrees. Subtracting a negative adds its magnitude — the number line runs 7 degrees down to zero and 9 more below it. Signed-number temperature problems test exactly this crossing-zero step, and the 2-degree distractor comes from subtracting the digits while ignoring the sign entirely.

Answer: A
Ten days is five times the two-day period, so the output scales by five: 3 × 5 = 15 rooms. Setting it as a proportion (3/2 = x/10, so x = 15) reaches the same answer. Rate problems reward finding the multiplier between the given period and the asked period before touching the other quantity — jumping straight to multiplication of the wrong pair is the planted error.

Answer: A
Distance equals rate times time: 55 mph × 3 hours = 165 miles. Adding the two numbers instead of multiplying them (55 + 3 = 58) is a common slip when a problem gives two values and a student defaults to addition. Dividing rate by time (18.33) confuses the distance formula with the time formula, and multiplying by one extra hour (4) gives 220, an off-by-one error on the time interval.

Answer: B
Time equals distance divided by rate: 240 ÷ 60 = 4 hours. Flipping the division to rate ÷ distance (60 ÷ 240 = 0.25) reverses the relationship and gives a fraction of an hour instead. Multiplying the two values instead of dividing gives an unreasonably large 14400. Adding one extra hour to the correct answer (5) is an off-by-one slip on the time interval.

Answer: C
Average speed equals distance divided by time: 180 ÷ 2.50 = 72 mph. Multiplying instead of dividing gives a far too large 450. Flipping the division (time ÷ distance) gives a tiny fraction, 0.0139. Truncating the 2.50-hour flight time down to a whole 2 hours before dividing gives 90, an off-by-one-interval error that drops the half hour.

Answer: D
Average speed for the whole trip is total distance divided by total time, not an average of the two speeds. Total distance is 240 miles; total time is 120÷40 + 120÷60 = 3 + 2 = 5 hours, so average speed = 240 ÷ 5 = 48 mph. Simply averaging the two speeds, (40+60)÷2 = 50, ignores that the driver spends more time at the slower speed. Dividing total distance by only the first leg's time gives 80, and using only the second speed gives 60.

Answer: A
Strip the fixed charge first: 225 − 65 = 160 of labor, then 160 ÷ 40 = 4 hours. As an equation, 65 + 40h = 225. The classic error divides the whole bill by the hourly rate without removing the parts charge, giving an answer between 5 and 6 that rounds to the planted 5. Fixed-plus-variable billing is among the most repeated Arithmetic Reasoning setups.

Answer: A
First find the time in hours, 5 ÷ 15 = 0.33 hour, then convert to minutes by multiplying by 60: 0.33 × 60 = 20 minutes. Multiplying speed by distance instead of dividing gives 75, an unrelated number. Flipping the ratio before converting (15 ÷ 5 × 60 = 180) reverses which quantity is on top. Using 100 instead of 60 to convert hours to minutes gives 33.3, the un-converted-unit slip.

Answer: B
First find the rate, 350 ÷ 7 = 50 mph, then find the extra distance, 50 × 2 = 100 miles, and add it to the original 350: 450 miles total. Reporting only the extra leg (100) forgets to add the original distance already covered. Multiplying the original distance by the total hours (7+2) instead of using the rate gives an inflated 3150. Using one extra hour beyond the actual total (7+2+1 hours) gives 500.

Answer: C
Price per pound is total cost divided by weight: $6.00 ÷ 4 = $1.50. Dividing pounds by cost instead (4 ÷ $6.00) reverses the ratio and gives a nonsense unit price of $0.67. Multiplying the two given numbers instead of dividing gives $24.00, far more than the apples actually cost. Subtracting the weight from the cost ($6.00 − 4) gives $2.00, which mixes two different units together.

Answer: D
Total cost is unit price times quantity: $2.25 × 9 = $20.25. Adding the price and the quantity instead of multiplying gives an unrealistically small $11.25. Dividing quantity by price (9 ÷ $2.25) gives $4.00, confusing this with a "how many can I buy" problem. Multiplying by one notebook too many, 10 instead of 9, gives $22.50, an off-by-one quantity error.

Answer: A
Find the price per bottle first, $18.00 ÷ 24 = $0.75, then multiply by the 9 bottles wanted: $6.75. Inverting the ratio, $18.00 × (24÷9), scales the price up instead of down and gives $48.00. Subtracting the desired quantity from the case cost ($18.00 − 9) gives an arbitrary $9.00. Dividing the full case cost by the desired quantity instead of the case quantity, $18.00 ÷ 9, gives $2.00, the reversed-denominator slip.

Answer: D
The increase is 12% of $900 = $108.00, so the new rent is $900 + $108.00 = $1,008.00. Stopping at $108.00 reports only the size of the raise, not the new total. Treating the change as a decrease instead of an increase, $900 × (1−0.12), gives $792.00, the opposite direction. Misplacing a decimal and applying 1.2% instead of 12% gives $910.80, far too small a raise.

Answer: C
Average equals the sum of the scores divided by how many there are: (82+90+76+88) ÷ 4 = 336 ÷ 4 = 84. Dividing by 3 instead of 4, an off-by-one count error, gives 112. Forgetting to divide at all and reporting the raw sum gives 336. Averaging only the first two scores and ignoring the other two gives 86, (82+90)÷2.

Answer: A
The cycle draws in the air-fuel mixture (intake), squeezes it (compression), ignites it to drive the piston (power), and expels the burnt gases (exhaust). The memory hook 'suck, squeeze, bang, blow' preserves the order. Auto Information asks the sequence directly and through which-stroke-does-X variants — spark timing at the top of compression, valves open during intake and exhaust.

Answer: A
The alternator is driven by an accessory belt off the crankshaft and generates alternating current, which is converted to direct current, to recharge the battery and supply the vehicle's ongoing electrical load while the engine runs. Storing energy for starting is the battery's job, cranking the engine over is the starter motor's job, and igniting the air-fuel mixture is the spark plug's job, not the alternator's.

Answer: B
The piston first pulls in the air-fuel charge (intake), then travels back up to squeeze it into a smaller volume (compression), the spark ignites the compressed charge and pushes the piston down to produce force (power), and finally the piston pushes the spent gases out (exhaust) before the cycle repeats. The wrong orders scramble this sequence in ways that would leave the mixture ignited before it is compressed, which cannot generate useful power.

Answer: B
Compression happens with both valves sealed shut so none of the charge can escape; the rising piston squeezes it into a much smaller volume, raising its pressure and temperature so it burns more completely and forcefully once ignited. Choice A describes valve overlap, which is a brief timing event, not the compression stroke itself. Choices C and D describe the exhaust and intake strokes, which occur with one valve open, the opposite of compression's sealed-cylinder condition.

Answer: B
The camshaft's lobes push open the intake and exhaust valves at precisely the right point in each cylinder's cycle, then let springs close them again. Because a four-stroke cylinder needs one full valve cycle every two crankshaft revolutions, a timing belt, chain, or gears spin the camshaft at exactly half crankshaft speed. Converting piston motion into rotation is the crankshaft's job, spraying fuel is the injector's job, and igniting the mixture is the spark plug's job.

Answer: D
A set of compression rings presses against the cylinder wall to keep combustion pressure from leaking past the piston, while an oil control ring wipes excess oil off the wall and returns it to the pan so it does not burn in the combustion chamber. Letting air and fuel enter is a valve's job, converting piston motion to rotation happens through the connecting rod and crankshaft, and coolant flows through passages in the block and head, not through the rings.

Answer: A
Blue smoke is the classic signature of burning oil: it is seeping past worn rings or hardened valve-guide seals into the combustion chamber, where it partially burns and produces a bluish haze, often worse right after the engine has been sitting and oil has drained down past the rings. A too-rich mixture typically produces black, sooty smoke from unburned fuel, while coolant burning in a cylinder produces sweet-smelling white smoke, not blue. A failing catalytic converter does not change exhaust smoke color this way.

Answer: B
The air filter is a porous element that traps dust, dirt, and other particles from the outside air before it reaches the intake system and cylinders, protecting the cylinder walls, piston rings, and sensors from abrasive wear. It does not actively cool the air, mix fuel (that is the injector's or, in older engines, the carburetor's job), and any noise reduction it provides is incidental, not its purpose. A clogged filter restricts airflow and can hurt performance and fuel economy.

Answer: C
Fuel injection uses an electronic control unit reading sensors such as airflow, throttle position, and oxygen content to command injectors to spray a precisely metered amount of fuel, adjusting instantly for conditions. A carburetor is a purely mechanical device that uses the vacuum created by intake airflow through a narrowed venturi to draw fuel from a float bowl and mix it with air, with far less precision and no direct feedback correction. Choices A and B reverse which system does which.

Answer: D
A turbocharger's turbine sits in the exhaust stream and is spun by the energy of escaping exhaust gas, which in turn drives a compressor wheel that pressurizes intake air; because it depends on exhaust flow, it can lag briefly at low engine speed before enough exhaust energy builds up. A supercharger's compressor is instead turned directly by a belt off the crankshaft, so its boost builds in direct proportion to engine speed with no such lag. Choices B through D swap or misstate these drive methods.

Answer: A
A clogged fuel filter starves the engine of fuel exactly when it needs the most, so the classic symptoms are hesitation, power loss, rough running, or stalling under acceleration, heavy load, or hard uphill driving, along with possible hard starting. A misfire traced to one cylinder's weak spark points instead to an ignition-system part such as a spark plug or coil. A cold-engine squeal usually points to a belt, and blue smoke points to burning oil, not a fuel restriction.

Answer: B
The battery is a chemical energy-storage device that discharges a large burst of current to spin the starter motor and crank the engine, and it also powers lights, accessories, and electronics whenever the engine is not running. It does not generate electricity while the engine runs; that ongoing charging job belongs to the alternator, which also tops the battery back up. The battery has no role in coolant temperature or in converting vacuum to electricity.

Answer: C
Turning the key sends a small control current to the solenoid, which closes heavy internal contacts to pass the battery's large starting current to the starter motor, and on most starters it also pushes the small pinion gear into mesh with the flywheel or flexplate's ring gear so the motor can crank the engine. It is not a backup power source, does not generate charging current, and has no role in fuel pressure regulation.

Answer: D
The spark plug delivers a high-voltage spark across its gap at a precisely timed moment, igniting the compressed air-fuel charge so it burns and drives the piston down on the power stroke. This ignition role is specific to gasoline engines; diesel engines instead rely on the heat of compression alone to ignite their fuel, using glow plugs only to assist cold starting. Metering fuel is the injector's job, valve timing is the camshaft's job, and compressing the mixture is the piston's job during its upward stroke.

Answer: B
Because the charging system tests normal once the engine is running, the alternator is doing its job; the problem is that the battery itself is no longer holding the charge it receives, which is typical of an old or damaged battery reaching the end of its service life. This is the classic trap of blaming the alternator for every hard-starting complaint: if charging voltage checks out fine, the alternator is not the cause. A thermostat has no electrical role, and a slipping belt would show up as low or no charging voltage, which was not the case here.

Answer: C
Warning-light activation and dimming lights while the engine is running are classic signs that the charging system is not keeping up with electrical demand, pointing to a failing alternator rather than the battery itself; the battery in this case is simply not being recharged after each trip, so it runs down. A fuel filter has no connection to the electrical system, and a thermostat regulates coolant temperature, not charging voltage. A simple end-of-life battery would not typically cause the dash light and dimming symptoms while driving.

Answer: C
Beyond reducing friction between moving parts, engine oil absorbs and carries heat away from areas the cooling system cannot easily reach, such as the underside of pistons and bearing surfaces, and it holds soot, metal particles, and other contaminants in suspension so the oil filter can remove them rather than letting them scratch engine surfaces. Oil plays no role in ignition, valve timing, converting piston motion to rotation, or cooling exhaust gases; those are handled by other systems.

Answer: A
The thermostat is a temperature-sensitive valve that blocks coolant from reaching the radiator while the engine is still cold, letting the engine warm up quickly, then opens once the coolant reaches its rated operating temperature so the radiator can begin cooling it. Circulating coolant is the water pump's job, filtering debris is not a function coolant systems typically perform this way, and exposing coolant to airflow to shed heat is the radiator's job, not the thermostat's.

Answer: D
The water pump uses an impeller, spun by a belt or the timing chain, to keep coolant continuously moving through the engine block, hoses, heater core, and radiator so heat can be picked up and carried away. Opening only once the engine warms up describes the thermostat's behavior, dissipating heat into the air is the radiator's job, and storing reserve coolant is closer to the overflow or coolant reservoir's role, not the pump's.

Answer: C
At highway speed, air rams through the radiator on its own from the car's forward motion, masking a bad cooling fan; at idle or in slow traffic there is little natural airflow, so if the fan is not engaging or has failed, heat builds up specifically under those low-speed conditions and eases once the car speeds up. A thermostat stuck closed or a seized water pump would cause overheating at all speeds, not just at idle, and a clogged air filter affects engine intake air, not cooling airflow through the radiator.

Answer: C
During a turn, the outer wheel travels a larger arc than the inner wheel and so must rotate faster; the differential uses a set of gears to send power to both drive wheels while allowing that speed difference, preventing tire scrubbing and drivetrain strain. Forcing both wheels to spin at identical speed would cause exactly the scrubbing problem the differential exists to avoid. Disconnecting engine power for shifting is the clutch's job, and smoothing power through a range of angles describes a CV joint, not a differential.

Answer: D
A thermostat stuck closed seals off the radiator entirely, so heat has nowhere to go and the engine overheats even though nothing else looks wrong; a failing water pump usually announces itself with a leak at its weep hole, a growling bearing, or, on belt-driven pumps, a belt problem that also knocks out other accessories, none of which are present here. A thermostat stuck open would instead make the engine run cooler than normal, the opposite problem, and engine oil level affects lubrication, not coolant temperature control.

Answer: A
The radiator is a network of thin tubes and fins that the heated coolant flows through; airflow from the vehicle's motion and, at low speeds, an engine-driven or electric fan pulls heat out of the coolant and releases it into the outside air, so the cooled coolant can return to the engine and absorb more heat. Pumping coolant is the water pump's job, blocking flow until warm-up is the thermostat's job, and generating a temperature signal is handled by a separate coolant temperature sensor, not the radiator itself.

Answer: B
The clutch uses a friction disc that a pressure plate normally clamps against the spinning flywheel, transmitting engine power to the transmission; pressing the clutch pedal releases that clamping force, momentarily disconnecting the engine from the drivetrain so the driver can change gears or come to a stop without the engine dying. Automatically selecting a gear is what an automatic transmission's controls do, torque multiplication through a fluid coupling describes a torque converter, and allowing wheels to spin at different speeds is the differential's job.

Answer: C
An automatic transmission relies on a torque converter, a fluid-coupling device that transfers engine power through moving transmission fluid rather than a rigid mechanical link, letting the vehicle come to a stop in gear without stalling and without the driver operating a clutch pedal. A manual transmission instead uses a friction clutch disc, engaged and disengaged by the driver's pedal. A differential manages power split between wheels, and CV joints transmit power through a range of motion at the axles; neither replaces the clutch's engagement function.

Answer: A
Because the front wheels both steer and move up and down with the suspension, the axle shafts driving them must constantly change angle; CV joints are specially designed to keep transmitting power at a constant rotational speed through that changing angle, unlike simpler universal joints, which can introduce speed fluctuations at sharp angles and are more often used on longer, straighter driveshafts. Allowing unequal wheel speeds while turning is the differential's job, disengaging power is the clutch's job, and converting piston motion to rotation happens at the crankshaft.

Answer: D
The names describe exactly which wheels receive engine power: front-wheel drive sends power only to the front pair, rear-wheel drive sends it only to the rear pair, and all-wheel drive sends power to all four wheels, either continuously or automatically as needed, for added traction on slippery surfaces. The other choices reverse which axle each layout powers or misdescribe all-wheel drive as powering a single wheel, when in fact it is defined by driving multiple axles rather than just one.

Answer: C
A CV joint operates at its most extreme angle during sharp turns, so a joint that has lost its lubricating grease and picked up grit and moisture through a torn rubber boot tends to click or pop specifically under that condition while staying quiet on straight roads. Brake rotor wear produces noise tied to braking, not steering angle, low oil affects the valve train regardless of steering input, and a restricted catalytic converter would cause a loss of power or noise unrelated to turning sharply.

Answer: D
In a disc brake system, a rotor (disc) rotates with the wheel, and a caliper straddling the rotor's edge clamps a pair of pads against both of its faces when hydraulic pressure is applied, creating friction that slows the wheel. A shoe, drum, and wheel cylinder instead describe a drum brake system, while the master cylinder and brake booster are shared components mounted near the pedal, not parts located at each wheel, and an anti-lock sensor is an added feature layered on top of the basic disc hardware.

Answer: A
Hydraulic pressure pushes the wheel cylinder's pistons apart, forcing the curved brake shoes outward against the inner surface of the drum that rotates with the wheel, and that friction slows the wheel down. A caliper squeezing pads against a rotor describes a disc brake, not a drum brake, and there is no rotor at all in a drum-brake wheel. A vacuum diaphragm is part of a brake booster's pedal-assist mechanism, not the friction-generating element at the wheel.

Answer: B
Pressing the pedal pushes a piston inside the master cylinder, pressurizing the brake fluid in the lines; because that fluid is essentially incompressible, the pressure is transmitted almost instantly and equally to the piston in each wheel's caliper or wheel cylinder, which then applies the actual clamping or pushing force. A parking brake, not the main service brakes, typically uses a cable. The alternator has no role in braking, and while a vacuum booster can assist pedal effort, it does not pressurize the fluid without the driver first pressing the pedal.

Answer: C
ABS uses wheel-speed sensors to detect when a wheel is about to stop rotating faster than the vehicle is decelerating, and it rapidly pulses that wheel's brake pressure on and off many times per second to keep the tire rolling and gripping instead of sliding, preserving steering control. A brake booster only reduces the pedal effort needed to apply the brakes and does not sense or prevent lockup on its own; this is a common point of confusion, but boost and anti-lock control are separate functions. The master cylinder generates pressure rather than modulating it, and the parking brake is a mechanically separate system.

Answer: D
A rotor that has warped or developed uneven thickness creates a periodic high spot that the caliper pads ride over once per wheel revolution, producing the pulsation felt in the pedal and steering wheel, especially noticeable at higher speed where the rotor spins faster. Air in the lines or low fluid typically produce a soft, spongy, or sinking pedal feel rather than a rhythmic pulsation, and a failing booster would make the pedal harder to press, not vibrate, so the firm pedal feel here argues against both fluid and booster problems.

Answer: A
A firm-but-slowly-sinking pedal under continuous, steady pressure is the classic sign of an internal bypass inside the master cylinder, where worn piston seals let fluid leak past internally from the pressurized side to the low-pressure side without any fluid escaping the system, so no external leak is ever seen. This differs from air in the lines, which produces an immediately spongy, low pedal rather than one that firmly holds and then slowly sinks, and from a warped rotor, which causes pulsation during active braking rather than pedal creep while stopped. The parking brake operates independently of the hydraulic service-brake circuit.

Answer: A
Arteries carry blood away from the heart ('A' for artery and away), veins return it, and capillaries are the microscopic exchange vessels connecting the two. Most arterial blood is oxygen-rich, but the definition is direction, not oxygen content — the pulmonary artery carries oxygen-poor blood away from the heart, the exception General Science uses to punish the oxygen-based shortcut.

Answer: C
The order outward is Mercury, Venus, Earth, Mars, then the gas and ice giants. Venus is the common wrong pick because it is the hottest planet — its dense carbon dioxide atmosphere traps heat — but hottest and closest are different superlatives, and the question asks distance. General Science regularly splits such near-miss superlatives across the choices.

Answer: A
Water freezes and melts at 32°F (0°C) and boils at 212°F (100°C) at sea level. The Celsius values 0 and 100 are planted as Fahrenheit answers — the scale-swap trap this question family always sets. Anchoring both pairs (32/212 Fahrenheit, 0/100 Celsius) closes out every version of the phase-change temperature question General Science asks.

Answer: A
To deteriorate is to decline in condition or quality — the rust is degrading the supports' integrity, not merely tinting them. Discolor understates the meaning (a frequent distractor pattern: a milder cousin of the right answer), while strengthen and support invert it. When two choices differ only in severity, the tested word's dictionary weight decides — deterioration is decay, not cosmetics.

Answer: B
Resistance equals voltage divided by current: R = V / I = 24 / 3 = 8 ohms. Choice D is the product of voltage and current (which is actually power in watts, not resistance), a mix-up between the two Ohm's law forms. Choice C mistakenly subtracts current from voltage. Choice A divides by the wrong number. Remembering that resistance is voltage over current, not voltage times current, keeps the two formulas separate.

Answer: C
Power equals voltage times current: P = I x V = 5 x 120 = 600 watts. Choice B comes from dividing voltage by current instead of multiplying, confusing the power formula with a resistance calculation. Choice A mistakenly subtracts current from voltage. Choice D results from multiplying by 5 twice (600 x 5), a duplication error. Multiplying voltage and current directly, without dividing or adding, gives the correct wattage.

Answer: C
Power can be found from current and resistance using P = I-squared x R = (2 x 2) x 10 = 40 watts. Choice B skips the squaring step and simply multiplies current by resistance once (2 x 10 = 20), a common shortcut error. Choice A divides resistance by current instead. Choice D squares the resistance instead of the current. Squaring the current first, then multiplying by resistance, is the key step this formula requires.

Answer: B
Ohm's law states current equals voltage divided by resistance: I = V / R = 12 / 4 = 3 amps. Choice D comes from multiplying voltage by resistance instead of dividing, which actually gives power's numeric setup, not current. Choice C reverses the division to R / V. Choice A results from mistakenly dividing by 8 instead of 4. Keeping the formula I = V / R straight, with voltage on top, avoids all three errors.

Answer: D
Ohm's law gives voltage as current times resistance: V = I x R = 2 x 6 = 12 volts. Choice A comes from dividing resistance by current instead of multiplying. Choice B is the sum of current and resistance rather than their product, a common mix-up when a candidate forgets which operation the law calls for. Choice C results from adding instead of multiplying incorrectly. Multiplying current by resistance is the only path to the correct voltage.