Pipe A fills a tank in 15 hours. Pipe B fills it in 10 hours. If both pipes are open, in how much time will the tank be filled?
A
5 hours
B
6 hours
C
7.5 hours
D
8 hours
Correct Answer:
B. 6 hours
Explanation:
Combined rate = 1/15 + 1/10 = 2/30 + 3/30 = 5/30 = 1/6. Time = 6 hours
A train travels at 60 km/h. How long will it take to cover 300 km?
A
4 hours
B
5 hours
C
6 hours
D
3 hours
Correct Answer:
B. 5 hours
Explanation:
Time = Distance/Speed = 300/60 = 5 hours
A boat travels downstream at 12 km/h and upstream at 8 km/h. What is the speed of the current?
A
1 km/h
B
2 km/h
C
3 km/h
D
4 km/h
Correct Answer:
B. 2 km/h
Explanation:
Speed of current = (Downstream speed - Upstream speed)/2 = (12 - 8)/2 = 2 km/h
Rs. 5000 is invested at 12% per annum simple interest. What will be the amount after 3 years?
A
Rs. 6500
B
Rs. 6800
C
Rs. 6200
D
Rs. 7000
Correct Answer:
B. Rs. 6800
Explanation:
SI = (5000 × 12 × 3)/100 = 1800. Amount = 5000 + 1800 = Rs. 6800
If 25% of a number is 80, what is 60% of that number?
Explanation:
If 25% = 80, then number = 320. 60% of 320 = 0.6 × 320 = 192
A shopkeeper offers a 30% discount on marked price. If the marked price is Rs. 1000, what is the selling price?
A
Rs. 600
B
Rs. 700
C
Rs. 800
D
Rs. 900
Correct Answer:
B. Rs. 700
Explanation:
Discount = 30% of 1000 = 300. Selling price = 1000 - 300 = Rs. 700
If a number is increased by 40% and then decreased by 30%, the net change in the number is:
A
10% increase
B
2% decrease
C
2% increase
D
No change
Correct Answer:
C. 2% increase
Explanation:
Let number = 100. After 40% increase = 140. After 30% decrease = 140 × 0.7 = 98. Net change = 102 - 100 = 2% increase.
A train travels 480 km at a speed of 60 km/h. If it increases its speed by 20%, how much time will it save?
A
1 hour
B
1.5 hours
C
2 hours
D
2.5 hours
Correct Answer:
A. 1 hour
Explanation:
Original time = 480/60 = 8 hours. New speed = 72 km/h. New time = 480/72 = 6.67 hours. Time saved = 8 - 6.67 = 1.33 ≈ 1 hour (approximately 1 hour 20 minutes).
Simple interest on a sum for 3 years at 8% p.a. is Rs. 1200. What is the principal?
A
Rs. 4000
B
Rs. 5000
C
Rs. 6000
D
Rs. 7000
Correct Answer:
B. Rs. 5000
Explanation:
SI = P × R × T / 100. 1200 = P × 8 × 3 / 100. P = (1200 × 100) / 24 = 5000.
A sum of Rs. 12,000 is invested at 10% p.a. compound interest. What will be the amount after 2 years?
A
Rs. 14,520
B
Rs. 14,000
C
Rs. 13,200
D
Rs. 15,000
Correct Answer:
A. Rs. 14,520
Explanation:
A = P(1 + R/100)^T = 12000(1.1)^2 = 12000 × 1.21 = 14,520.
