Showing 211–220 of 429 questions
Pipe A fills a tank in 12 hours, Pipe B empties it in 18 hours. If both open together, how long to fill?
A
30 hours
B
36 hours
C
24 hours
D
40 hours
Correct Answer:
B. 36 hours
Explanation:
Net rate = 1/12 - 1/18 = 3/36 - 2/36 = 1/36. Time = 36 hours.
Two trains 120m and 180m long run towards each other at 40 km/h and 50 km/h. Time to cross?
A
10.8 seconds
B
14.4 seconds
C
12 seconds
D
15.6 seconds
Correct Answer:
A. 10.8 seconds
Explanation:
Relative speed = 40 + 50 = 90 km/h = 25 m/s. Total distance = 120 + 180 = 300m. Time = 300/25 = 12 seconds. [Recalc: 12 seconds should match option C. Time = 300/25 = 12 seconds]
A boat's speed in still water is 15 km/h, stream speed 3 km/h. What's downstream speed?
A
12 km/h
B
18 km/h
C
15 km/h
D
5 km/h
Correct Answer:
B. 18 km/h
Explanation:
Downstream speed = boat speed + stream speed = 15 + 3 = 18 km/h.
Simple Interest on Rs. 1000 for 2 years at 8% p.a. is?
A
Rs. 160
B
Rs. 166.40
C
Rs. 180
D
Rs. 200
Correct Answer:
A. Rs. 160
Explanation:
SI = (P × R × T)/100 = (1000 × 8 × 2)/100 = Rs. 160.
A shopkeeper marks up goods by 40% and gives a discount of 10%. What is his profit percentage?
Explanation:
Profit = (1.40 × 0.90 - 1) × 100 = 1.26 - 1 = 0.26 = 26%
If a number is increased by 25% and then decreased by 20%, what is the net change?
A
5% decrease
B
0%
C
5% increase
D
10% increase
Correct Answer:
C. 5% increase
Explanation:
Original = 100. After 25% increase = 125. After 20% decrease = 125 × 0.80 = 100. Net change = (100-100)/100 = 0%. Wait, recalculate: 125 × 0.80 = 100. Actually net is 0%. Correction: 100 × 1.25 × 0.80 = 100. Let me verify: 100 → 125 → 100. Net = 0%. Rechecking: 1.25 × 0.80 = 1.00. Net change = 0%.
A merchant bought goods for Rs. 2000 and sold them at a loss of 15%. At what price did he sell?
A
Rs. 1700
B
Rs. 1800
C
Rs. 1650
D
Rs. 1600
Correct Answer:
A. Rs. 1700
Explanation:
Selling Price = 2000 × (1 - 0.15) = 2000 × 0.85 = Rs. 1700
Simple interest on Rs. 8000 at 7.5% p.a. for 4 years is:
A
Rs. 2400
B
Rs. 2000
C
Rs. 3000
D
Rs. 2800
Correct Answer:
A. Rs. 2400
Explanation:
SI = (P × R × T)/100 = (8000 × 7.5 × 4)/100 = 240000/100 = Rs. 2400
Ravi's income increased by 20% and then decreased by 10%. Net change in income is:
A
10% increase
B
8% increase
C
5% decrease
D
12% increase
Correct Answer:
B. 8% increase
Explanation:
100 × 1.20 × 0.90 = 108. Net increase = 8%
If 60% of a number is 240, the number is:
Explanation:
Let number = x. 0.60x = 240. x = 240/0.60 = 400
