Central Exam — Quantitative Aptitude
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Showing 611–620 of 1,106 questions
Q.611
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?
Correct Answer:
B. 3:2
Explanation:
Downstream = 15 + 3 = 18. Upstream = 15 - 3 = 12. Ratio = 18:12 = 3:2.
Q.612
Easy
Numbers
If 75 workers can build a wall in 120 days, how many days will 90 workers take?
Correct Answer:
C. 100 days
Explanation:
Work = Workers × Days = 75 × 120 = 9000. Days = 9000/90 = 100 days.
Q.613
Medium
Numbers
A price is increased by 30%, then decreased by 30%. What is the net change?
Correct Answer:
B. 9% decrease
Explanation:
Let original = 100. After 30% increase = 130. After 30% decrease = 130 × 0.7 = 91. Net = 9% decrease.
Q.614
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?
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.
Q.615
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?
Correct Answer:
A. Rs. 320
Explanation:
Selling Price = 500 × 80/100 = Rs. 400. If profit is 25%, then CP = 400 × 100/125 = Rs. 320
Q.616
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?
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
Q.617
Easy
Numbers
A train 250m long crosses a platform 150m long in 20 seconds. What is the speed of the train?
Correct Answer:
B. 72 km/h
Explanation:
Distance covered = 250 + 150 = 400m. Speed = 400/20 = 20 m/s = 20 × 18/5 = 72 km/h
Q.618
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?
Correct Answer:
A. 4 hours
Explanation:
Downstream speed = 12 + 3 = 15 km/h. Time = 60/15 = 4 hours
Q.619
Easy
Numbers
If a number is decreased by 40%, it becomes 300. What is the original number?
Correct Answer:
A. 500
Explanation:
Let original number be x. x × 60/100 = 300. x = 300 × 100/60 = 500
Q.620
Easy
Numbers
A man buys goods for Rs. 2500 and sells them at a loss of 8%. What is the selling price?
Correct Answer:
A. Rs. 2300
Explanation:
Selling Price = 2500 × 92/100 = Rs. 2300