Question:
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:
[A].60 gallons
100 gallons
120 gallons
180 gallons
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:
[A].
[B].
[C].
[D].
Answer: Option C
Explanation:
| Work done by the waste pipe in 1 minute = | 1 | – | 1 | + | 1 | ||
| 15 | 20 | 24 |
| = | 1 | – | 11 | ||
| 15 | 120 |
| = – | 1 | . [-ve sign means emptying] |
| 40 |
| Volume of | 1 | part = 3 gallons. |
| 40 |
Volume of whole = (3 x 40) gallons = 120 gallons.