A train 180m long crosses another train 220m long coming towards it in 9 seconds. If the first train's speed is 40 km/h, what is the speed of the second train?
A
50 km/h
B
32 km/h
C
48 km/h
D
36 km/h
Correct Answer:
B. 32 km/h
Explanation:
Total distance = 180 + 220 = 400m. Relative speed = 400/9 m/s = 160 km/h. Speed of second train = 160 - 40 = 32 km/h
Three pipes A, B, and C can fill a tank in 6, 8, and 12 hours respectively. If all three are opened together, what fraction of the tank is filled in 1 hour?
A
9/24
B
12/24
C
15/24
D
18/24
Explanation:
Combined rate = 1/6 + 1/8 + 1/12 = 4/24 + 3/24 + 2/24 = 9/24
A product's price increased by 25%, then decreased by 20%. What is the net change?
A
0% (no change)
B
+5%
C
-5%
D
+10%
Explanation:
Let original price = 100. After 25% increase = 125. After 20% decrease = 125 × 80/100 = 100. Net = +5% gain
A boat goes 30 km upstream in 6 hours and 30 km downstream in 3 hours. What is the speed of the boat in still water?
A
7.5 km/h
B
6.5 km/h
C
8 km/h
D
5 km/h
Correct Answer:
A. 7.5 km/h
Explanation:
Upstream speed = 30/6 = 5 km/h. Downstream speed = 30/3 = 10 km/h. Boat speed = (5+10)/2 = 7.5 km/h
Rs. 1000 is invested at 10% per annum compound interest for 2 years. What is the final amount?
A
Rs. 1210
B
Rs. 1200
C
Rs. 1100
D
Rs. 1320
Correct Answer:
A. Rs. 1210
Explanation:
Amount = 1000(1 + 10/100)² = 1000 × 1.1 × 1.1 = Rs. 1210
X and Y together can complete a work in 18 days. X alone can complete it in 30 days. In how many days can Y alone complete the work?
A
45 days
B
38 days
C
42 days
D
35 days
Correct Answer:
A. 45 days
Explanation:
Y's rate = 1/18 - 1/30 = 5/90 - 3/90 = 2/90 = 1/45. Y can complete in 45 days
A man buys goods for Rs. 2500 and sells them at a loss of 8%. What is the selling price?
A
Rs. 2300
B
Rs. 2200
C
Rs. 2400
D
Rs. 2100
Correct Answer:
A. Rs. 2300
Explanation:
Selling Price = 2500 × 92/100 = Rs. 2300
If a number is decreased by 40%, it becomes 300. What is the original number?
Explanation:
Let original number be x. x × 60/100 = 300. x = 300 × 100/60 = 500
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
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
