Question

Two taps ‘A’ and ‘B’ can fill a water reservoir in 8 and 6 hours respectively. A third tap ‘C’ can empty the tank completely in 24 hours. How long would it take to fill the empty tank when all the taps are open?

Options

• 4 hours

• 5 hours

• 6 hours

• 3 hours

Answer 1

4 hours

Explanation:

Tap A can fill in 8 hr, B in 6 hr, C can empty reservoir in 24 hr

All 3 can fill a reservoir in 1 hr

`=1/8+1/6-1/24=(6+8-2)/48=12/48`

All three can fill the whole reservoir in `48/12` i.e. 4 hr