A tank can be filled by pipes A, B, C in 10, 15, 20 hours respectively. Pipe D empties in 30 hours. All open together, how long to fill?

The correct answer is C: 6 hours. Net rate = 1/10 + 1/15 + 1/20 - 1/30 = 6/60 + 4/60 + 3/60 - 2/60 = 11/60. Time = 60/11 ≈ 5.45, closest is 6.

Worker A completes a job in 15 days. Worker B completes the same job in 20 days. If they work together, how many days will it take?

The correct answer is C: 8.57 days. Combined rate = 1/15 + 1/20 = 7/60. Time = 60/7 ≈ 8.57 days

B can do a job in 15 days. What is B's work rate per day?

The correct answer is B: 1/15. This question asks us to find B's daily work rate when the total job can be completed in 15 days. Step 1: Understand work rate definition Work rate is the fraction of total work completed per day. $$\text{Work Rate} = \frac{\text{Total Work}}{\text{Total Days}}$$ Step 2: Define total work as 1 compl

What is the smallest 4-digit number that is divisible by 18?

The correct answer is A: 1008. Smallest 4-digit number is 1000. For divisibility by 18, number must be divisible by both 2 and 9. 1000 ÷ 18 = 55.55... Next: 1008 ÷ 18 = 56. So 1008 is the answer.

A train 250 meters long passes a platform 150 meters long in 20 seconds. Find the speed of the train.

The correct answer is C: 72 km/h. Total distance = 250 + 150 = 400 meters. Time = 20 seconds. Speed = 400/20 = 20 m/s = 20 × 18/5 = 72 km/h

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Numbers

Quantitative aptitude questions for competitive exams

196 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–40 of 196

Topics in Quantitative Aptitude

All Numbers 499 HCF and LCM 150 Profit and Loss 102 Time and Work 101 Percentage 101 Simple Interest 50 Average 48

Q.31 Easy Numbers

If a number is decreased by 40%, it becomes 300. What is the original number?

A 500

B 420

C 480

D 550

Correct Answer: A. 500

EXPLANATION

Let original number be x. x × 60/100 = 300. x = 300 × 100/60 = 500

Test

Q.32 Easy Numbers

A boat's speed in still water is 12 km/h and the speed of current is 3 km/h. How long will it take to travel 60 km downstream?

A 4 hours

B 3.75 hours

C 5 hours

D 4.5 hours

Correct Answer: A. 4 hours

EXPLANATION

Downstream speed = 12 + 3 = 15 km/h. Time = 60/15 = 4 hours

Test

Q.33 Easy Numbers

A train 250m long crosses a platform 150m long in 20 seconds. What is the speed of the train?

A 54 km/h

B 72 km/h

C 45 km/h

D 60 km/h

Correct Answer: B. 72 km/h

EXPLANATION

Distance covered = 250 + 150 = 400m. Speed = 400/20 = 20 m/s = 20 × 18/5 = 72 km/h

Test

Q.34 Easy Numbers

Two pipes A and B can fill a tank in 12 hours and 15 hours respectively. If both pipes are opened together, in how many hours will the tank be filled?

A 6.67 hours

B 5.5 hours

C 7.5 hours

D 8 hours

Correct Answer: A. 6.67 hours

EXPLANATION

Combined rate = 1/12 + 1/15 = 5/60 + 4/60 = 9/60 = 3/20. Time = 20/3 = 6.67 hours

Test

Q.35 Easy Numbers

A shopkeeper marks an item at Rs. 500. He gives a discount of 20% and still makes a profit of 25%. What is the cost price?

A Rs. 320

B Rs. 400

C Rs. 350

D Rs. 380

Correct Answer: A. Rs. 320

EXPLANATION

Selling Price = 500 × 80/100 = Rs. 400. If profit is 25%, then CP = 400 × 100/125 = Rs. 320

Test

Q.36 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.

Test

Q.37 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.

Test

Q.38 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%.

Test

Q.39 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.

Test

Q.40 Easy Numbers

A person invested Rs. 10000 in a scheme. After 2 years at 10% compound interest, the amount becomes:

A Rs. 12100

B Rs. 12000

C Rs. 11000

D Rs. 11500

Correct Answer: A. Rs. 12100

EXPLANATION

Amount = P(1 + R/100)^T = 10000(1.1)^2 = 10000 × 1.21 = Rs. 12100.

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