A pipe can fill a tank in 8 hours. After 3/5 of the tank is filled, four more pipes of half capacity

M4maths Previous Puzzles

29 Jun 2022 Pipes & Cisterns

A pipe can fill a tank in 8 hours. After 3/5 of the tank is filled, four more pipes of half capacity are opened to fill the tank. What is the total time taken to completely fill the tank ?

OPtion

1) 5 hours 39 minutes
2) 6 hours 52 minutes
3) 5 hours 26 minutes
4) 6 hours 48 minutes
5) 6 hours 24 minutes
6) 5 hours 52 minutes
7) 5 hours 48 minutes
8) 5 hours 30 minutes
9) 6 hours 26 minutes
10) None of these

Solution

Time taken by first pipe to fill the tank = 8 hours
.'. Time taken by first pipe to fill 3/5 of the tank = (3/5)/(1/8) = 24/5 hours
Remaining part of the tank to be filled = 1 - 3/5 = 2/5
Part of the tank filled by 1 existing pipe and 4 new pipes in 1 hour = 1/8 + 4x(1/16) = 3/8
Time taken by 5 pipes to fill remaining tank = (2/5)/(3/8) = 16/15 hours
.'. Total time taken = 24/5 + 16/15 = 88/15 hours = 5 hours 52 minutes.
Correct Option 6)

Correct Option: 6 Best Solution (0)