Question

Two pipes A and B can fill a tank in 20 hours and 24 hours respectively. If the two pipes opened at 5 in the morning, then at what time the pipe A should be closed to completely fill the tank exactly at 5 in the evening?

• A. 3 pm
• B. 2 pm
• C. 1 pm
• D. 11 am

Answer 1

Answer:

A. 3 pm

Total capacity of tank = LCM of 20, 24 = 120 Work done by B in 12 hours = 120/24 × 12 = 60 Remaining work was done by A, ⇒ A would take 60 × 20/120 hours = 10 hours. 5 A.M + 10 hours = 3 P.M