Question

A tap fills a cistern in 8 minutes and another tap empties it in 16 minutes. If both the taps are opened, then the time taken to fill it will be
1. 12 minutes
2. 16 minutes
3. 10 minutes
4. None of the above

Answer 1

Correct Answer - Option 2 : 16 minutes

Given:

A tap fills a cistern in 8 minutes and another tap empties it in 16 minutes

Calculation

Time taken to fill the cistern = 8 min

Part of cistern filled in 1 min = 1/8

Time taken to empty the cistern = 16 min

Part of cistern emptied in 1 min = 1/16

When both taps are opened simultaneously,

Part of cistern filled in 1 min = 1/8 - 1/16

⇒ 1/16

Time taken by both taps to fill the cistern = 16 minutes