Numbers
A train 200m long passes a bridge 300m long completely in 25 seconds. What is the speed of the train in km/h?
A 70.2 km/h
B 72 km/h
C 75.6 km/h
D 80 km/h
Correct Answer:
B. 72 km/h Explanation:
Total distance = 200 + 300 = 500m. Speed = 500/25 = 20 m/s = 20 × 3.6 = 72 km/h
A shopkeeper buys an item for Rs. 400 and marks it 50% above cost price. He gives a discount of 20% on marked price. What is his profit percentage?
Explanation:
MP = 400 × 1.5 = Rs. 600. SP = 600 × 0.8 = Rs. 480. Profit = (480-400)/400 × 100 = 20%
Worker A completes a job in 12 days. Worker B completes the same job in 15 days. If they work together, in how many days will they complete it?
A 6 days
B 6.67 days
C 7.5 days
D 8 days
Correct Answer:
B. 6.67 days Explanation:
Combined rate = 1/12 + 1/15 = (5+4)/60 = 9/60 = 3/20. Time = 20/3 = 6.67 days
A sum becomes Rs. 14400 after 2 years at 20% p.a. simple interest. What is the principal?
A Rs. 10000
B Rs. 10500
C Rs. 11000
D Rs. 12000
Correct Answer:
A. Rs. 10000 Explanation:
SI = P × R × T / 100 = P × 20 × 2 / 100 = 0.4P. Amount = P + 0.4P = 1.4P = 14400. P = 10000
A boat travels 48 km downstream in 3 hours and 32 km upstream in 4 hours. What is the speed of current?
A 2 km/h
B 3 km/h
C 4 km/h
D 5 km/h
Correct Answer:
A. 2 km/h Explanation:
Downstream speed = 48/3 = 16 km/h. Upstream speed = 32/4 = 8 km/h. Current = (16-8)/2 = 2 km/h
A number is increased by 30%, then decreased by 20%. Net change is what percent?
Explanation:
Let number = 100. After +30% = 130. After -20% of 130 = 130 × 0.8 = 104. Net increase = 4%
Pipe A fills a tank in 20 hours. Pipe B drains it in 30 hours. If both open together, how long to fill empty tank?
A 50 hours
B 60 hours
C 65 hours
D 70 hours
Correct Answer:
B. 60 hours Explanation:
Net rate = 1/20 - 1/30 = (3-2)/60 = 1/60. Time = 60 hours
A train 150m long passes a platform 250m long completely in 16 seconds. What is the train's speed?
A 56.25 km/h
B 60 km/h
C 67.5 km/h
D 72 km/h
Correct Answer:
A. 56.25 km/h Explanation:
Total distance = 150 + 250 = 400m. Speed = 400/16 = 25 m/s = 25 × 3.6 = 90 km/h. Wait, recalculating: 400m in 16s = 25 m/s = 90 km/h. Option should be different. Speed = 90 km/h but not in options. Using 16s: 400/16 = 25 m/s, 25×18/5 = 90. Rechecking: 400/16 = 25, 25×3.6 = 90 km/h
A merchant's cost price is Rs. 800. He marks 40% above CP and gives 25% discount. His profit/loss percent is?
A 5% profit
B 5% loss
C 10% profit
D 10% loss
Correct Answer:
A. 5% profit Explanation:
MP = 800 × 1.4 = 1120. SP = 1120 × 0.75 = 840. Profit = (840-800)/800 × 100 = 5%
What percentage of 480 is 72?
