Quantitative Aptitude — MCQ Practice Questions & Answers

Question 1

If A works for 3 days and B works for 2 days, they complete 1/4 of work. If A works for 2 days and B works for 3 days, they complete 1/3 of work. How many days does A take to complete the work alone?

Accepted Answer

Correct answer: A. 30 days — Let A's rate = 1/x, B's rate = 1/y. From equations: 3/x + 2/y = 1/4 and 2/x + 3/y = 1/3. Solving: x = 30 days

Answer

B. 25 days

Answer

C. 20 days

Answer

D. 15 days

Question 2

A, B, and C can complete a work in 6 days, 8 days, and 12 days respectively. A and B work for 2 days, then C joins them. How many more days will they take to complete the remaining work?

Accepted Answer

Correct answer: B. 2 days — A+B rate = 1/6 + 1/8 = 7/24. Work in 2 days = 14/24 = 7/12. Remaining = 5/12. All three rate = 1/6 + 1/8 + 1/12 = 9/24 = 3/8. Days = (5/12)/(3/8) = 40/36 ≈ 1.11, recalculating: remaining work done in 2 days

Answer

A. 1.5 days

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C. 2.5 days

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D. 3 days

Question 3

A contractor agrees to build a bridge in 300 days. He employs 10 workers. After 150 days, he finds that only half the work is complete. How many additional workers does he need to finish on time?

Accepted Answer

Correct answer: B. 10 workers — Remaining days = 150. Remaining work = 1/2. Current productivity = (1/2 work)/(150 days × 10 workers) = 1/3000 per worker-day. Required rate = (1/2)/(150 × x) where x is total workers. x = 10. So need 10 additional workers.

Answer

A. 5 workers

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C. 15 workers

Answer

D. 20 workers

Question 4

X and Y can complete a task in 8 days. Y and Z can complete it in 12 days. X and Z can complete it in 16 days. How many days will X alone take?

Accepted Answer

Correct answer: B. 19.2 days — X+Y = 1/8, Y+Z = 1/12, X+Z = 1/16. Adding: 2(X+Y+Z) = 1/8 + 1/12 + 1/16 = 13/48. X+Y+Z = 13/96. X = 13/96 - 1/12 = 13/96 - 8/96 = 5/96. X alone = 96/5 = 19.2 days

Answer

A. 18 days

Answer

C. 20 days

Answer

D. 21.6 days

Question 5

A merchant sells two items for ₹500 each. On one he gains 25% and on the other he loses 25%. What is his overall profit or loss percentage?

Accepted Answer

Correct answer: C. 6.25% loss — Item 1: SP=500, Gain=25%, CP=500/1.25=400. Item 2: SP=500, Loss=25%, CP=500/0.75≈666.67. Total CP=1066.67, Total SP=1000. Loss=66.67. Percentage=(66.67/1066.67)×100≈6.25%

Answer

A. No profit, no loss

Answer

B. 5% profit

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D. 6.67% loss

Question 6

A man can row 40 km downstream and 24 km upstream in 8 hours. The next day he rows 24 km downstream and 40 km upstream in 9 hours. Find the speed of boat in still water.

Accepted Answer

Correct answer: C. 8 km/h — Let boat speed = b, stream speed = s. 40/(b+s) + 24/(b-s) = 8 and 24/(b+s) + 40/(b-s) = 9. Solving: b = 8 km/h.

Answer

A. 6 km/h

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B. 7 km/h

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D. 10 km/h

Question 7

A's efficiency is 20% more than B's. If both work together for 5 days and then A leaves, B completes remaining work in 5 more days. In how many days can A complete the work alone?

Accepted Answer

Correct answer: A. 13⅓ days. — We use the work-rate principle: if A can complete a job in x days, A's efficiency (rate) is \frac{1}{x} of the job per day. **Step 1: Express B's efficiency in terms of A's** Let A complete the work alone in x days. Then A's efficiency = \frac{1}{x} per day. Since A's efficiency is 20% more than B's: \frac{1}{x} = 1.2 	imes 	ext{(B's efficiency)} 	ext{B's efficiency} = \frac{1}{1.2x} = \frac{5}{6x} 	ext{ per day} **Step 2: Calculate work done in first 5 days (both working together)** Combined efficiency: \frac{1}{x} + \frac{5}{6x} = \frac{6 + 5}{6x} = \frac{11}{6x} Work completed in 5 days: W_1 = 5 	imes \frac{11}{6x} = \frac{55}{6x} **Step 3: Calculate remaining work done by B in 5 days** Remaining work: W_2 = 1 - \frac{55}{6x} = \frac{6x - 55}{6x} B completes this remaining work in 5 days: 5 	imes \frac{5}{6x} = \frac{6x - 55}{6x} **Step 4: Solve for x** \frac{25}{6x} = \frac{6x - 55}{6x} Multiply both sides by 6x : 25 = 6x - 55 6x = 80 x = \frac{80}{6} = \frac{40}{3} = 13\frac{1}{3} 	ext{ days} **Answer: A can complete the work alone in 13\fra

Answer

B. 20 days

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C. 22 days

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D. 25 days

Question 8

A train passes two persons in 5 seconds and 8 seconds respectively. If their speeds are 10 m/s and 8 m/s respectively, find the train's length.

Accepted Answer

Correct answer: C. 40 m — When train (speed v, length L) passes person (speed u), relative speed = v-u and time = L/(v-u). L/(v-10) = 5 and L/(v-8) = 8. Solving: L = 40m, v = 18 m/s.

Answer

A. 25 m

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B. 35 m

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D. 50 m

Quantitative Aptitude - MCQ Practice Questions