Question

A cistern has a leak which would empty the cistern in 20 minutes. A tap is turned on which admits 4 liters a minute into the cistern, and it is emptied in 24 minutes. How many liters does the cistern hold?

Answer 1

Step-by-step explanation:

If a is the capacity of the cistern and b is the number of litres leaking per minute, then Capacity of the cistern in litres is a = 20b (1) Water added to the cistern in 24 minutes = 24*4 = 96 Therefore a = 24b - 96 (2)

From (1) and (), we get 20b = 24b-96 4b = 96 b = 24 Therefore, capacity of the cistern is 20b = 480 litres