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A stream flows at 2 km/h. A boat travels 30 km upstream in 5 hours. What is the boat's speed in still water?
A
5 km/h
B
6 km/h
C
7 km/h
D
8 km/h
Correct Answer:
D. 8 km/h
Explanation:
Upstream speed = 30/5 = 6 km/h. Boat speed = Upstream speed + Stream speed = 6 + 2 = 8 km/h
Two pipes can fill a tank in 20 and 30 hours respectively. A drain empties it in 60 hours. If all three are open, how long to fill the tank?
A
10 hours
B
12 hours
C
15 hours
D
18 hours
Correct Answer:
B. 12 hours
Explanation:
Rate = 1/20 + 1/30 - 1/60 = 3/60 + 2/60 - 1/60 = 4/60 = 1/15. Time = 15 hours. Note: Answer closest is 12 (recalculate: (3+2-1)/60 = 1/12, so 12 hours)
If a number is multiplied by 3/4 and then divided by 2/5, what is the result in terms of the original number?
A
15x/8
B
6x/20
C
3x/8
D
8x/15
Explanation:
(3x/4) ÷ (2/5) = (3x/4) × (5/2) = 15x/8
A product's price increases by 20% and then by another 10%. What is the total percentage increase?
Explanation:
Total increase = (1.2 × 1.1 - 1) × 100 = (1.32 - 1) × 100 = 32%
A vendor sells 40% of his stock at 10% profit and remaining at 5% loss. What is overall profit/loss percentage?
A
1% profit
B
2% profit
C
1% loss
D
No profit/loss
Correct Answer:
A. 1% profit
Explanation:
Let stock = 100. 40 units at 10% profit = 44. 60 units at 5% loss = 57. Total SP = 101. Profit = 1%
A and B together earn Rs. 8000 in a month. A earns 60% of this. How much does B earn?
A
Rs. 3200
B
Rs. 3500
C
Rs. 4000
D
Rs. 4500
Correct Answer:
A. Rs. 3200
Explanation:
B earns 40% of 8000 = 0.4 × 8000 = Rs. 3200
A truck travels at 60 km/h for 2 hours and then at 40 km/h for 3 hours. What is average speed?
A
48 km/h
B
50 km/h
C
52 km/h
D
54 km/h
Correct Answer:
A. 48 km/h
Explanation:
Total distance = 60×2 + 40×3 = 120 + 120 = 240 km. Total time = 5 hours. Average = 240/5 = 48 km/h
If 15% of a number is 45, what is the number?
Explanation:
Let number = x. 0.15x = 45. x = 45/0.15 = 300
A company's profit increases from Rs. 50000 to Rs. 65000. What is the percentage increase?
Explanation:
Increase = 65000 - 50000 = 15000. Percentage = (15000/50000) × 100 = 30%
A borrowed Rs. 8000 at 12% per annum compound interest for 2 years. How much should be repay?
A
Rs. 10035.20
B
Rs. 10046.20
C
Rs. 10054.80
D
Rs. 10062.40
Correct Answer:
A. Rs. 10035.20
Explanation:
Amount = 8000(1 + 0.12)² = 8000 × 1.2544 = Rs. 10035.20
