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Quantitative aptitude questions for competitive exams

500 Q 7 Topics Take Test

Difficulty: All Easy Medium Hard 91–100 of 500

Topics in Quantitative Aptitude

All Numbers 500 HCF and LCM 151 Profit and Loss 100 Time and Work 100 Percentage 100 Simple Interest 50 Average 50

Q.91 Hard Numbers

Two pipes A and B can fill a tank in 10 hours and 15 hours respectively. A third pipe C empties it in 20 hours. If all three are opened simultaneously, in how many hours will the tank be filled?

A 8.57 hours

B 9.23 hours

C 10.5 hours

D 12 hours

Correct Answer: A. 8.57 hours

EXPLANATION

Net rate = 1/10 + 1/15 - 1/20 = 6/60 + 4/60 - 3/60 = 7/60. Time = 60/7 ≈ 8.57 hours.

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Q.92 Medium Numbers

A price is increased by 30%, then decreased by 30%. What is the net change?

A No change

B 9% decrease

C 9% increase

D 15% decrease

Correct Answer: B. 9% decrease

EXPLANATION

Let original = 100. After 30% increase = 130. After 30% decrease = 130 × 0.7 = 91. Net = 9% decrease.

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Q.93 Easy Numbers

If 75 workers can build a wall in 120 days, how many days will 90 workers take?

A 80 days

B 90 days

C 100 days

D 110 days

Correct Answer: C. 100 days

EXPLANATION

Work = Workers × Days = 75 × 120 = 9000. Days = 9000/90 = 100 days.

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Q.94 Easy Numbers

A boat's speed in still water is 15 km/h and current speed is 3 km/h. What is the ratio of downstream to upstream speeds?

A 2:1

B 3:2

C 4:3

D 5:3

Correct Answer: B. 3:2

EXPLANATION

Downstream = 15 + 3 = 18. Upstream = 15 - 3 = 12. Ratio = 18:12 = 3:2.

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Q.95 Hard Numbers

A sum of money becomes Rs. 9000 in 2 years and Rs. 10125 in 3 years at compound interest. What is the rate of interest?

A 10%

B 12.5%

C 15%

D 20%

Correct Answer: B. 12.5%

EXPLANATION

Rate = (10125/9000 - 1) × 100 = (1.125 - 1) × 100 = 12.5%.

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Q.96 Easy Numbers

A man buys 50 pens at Rs. 3 each and sells them at Rs. 3.50 each. What is his profit percentage?

A 14.28%

B 16.67%

C 18.5%

D 20%

Correct Answer: B. 16.67%

EXPLANATION

CP = 50 × 3 = 150. SP = 50 × 3.5 = 175. Profit % = (25/150) × 100 = 16.67%.

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Q.97 Medium Numbers

If a cistern is filled by three pipes in 4, 6, and 12 hours respectively, how long will it take to fill if all three are opened together?

A 2 hours

B 2.4 hours

C 3 hours

D 3.5 hours

Correct Answer: A. 2 hours

EXPLANATION

Combined rate = 1/4 + 1/6 + 1/12 = 3/12 + 2/12 + 1/12 = 6/12 = 1/2. Time = 2 hours.

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Q.98 Medium Numbers

A train travelling at 90 km/h takes 8 seconds to cross another train travelling at 54 km/h in the opposite direction. What is the sum of their lengths?

A 200m

B 280m

C 320m

D 400m

Correct Answer: C. 320m

EXPLANATION

Relative speed = 90 + 54 = 144 km/h = 40 m/s. Distance = 40 × 8 = 320m = sum of lengths.

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Q.99 Easy Numbers

A number when increased by 15% becomes 575. What is the original number?

A 500

B 550

C 460

D 480

Correct Answer: A. 500

EXPLANATION

Let original number = x. x × 1.15 = 575. x = 575/1.15 = 500.

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Q.100 Medium Numbers

Two workers A and B can complete a job in 8 days and 12 days respectively. A starts the work and after 2 days, B joins. In how many more days will the work be completed?

A 3.6 days

B 4.2 days

C 4.8 days

D 5 days

Correct Answer: A. 3.6 days

EXPLANATION

Work by A in 2 days = 2/8 = 1/4. Remaining work = 3/4. Combined rate = 1/8 + 1/12 = 5/24. Time = (3/4)/(5/24) = 18/5 = 3.6 days.

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