## 3 pumps, working 8 hours a day, can empty a tank in 2 days. How many hours a day must 4 pumps work to empty the tank in 1 day?

- 9
- 10
- 11
- 12

*Answer and Explanation:*

**Correct Option: 4**

3 pumps working 8 hours a day for 2 days, can produce 3 * 8 * 2 = 48 pumping hours.

As per the question, same, 48 pumping hours, needs to be achieved by 4 pumps in 1 day.

$> \therefore $> as per the question,

48 pumping hours = 4 x 1 x n (where n is the number of hours 4 pumps has to work)

$> \therefore $> n = $> \frac{48}{4} $> = 12 hrs.