Question

If 15 pumps of equal capacity can fill a tank in 7 days, then how many extra pumps will be required to fill the tank in 5 days?

Answer 1

No. of pumps = 15
Days taken to fill the tank = 7
To find - No. of pumps required to fill the pump in 5 days = x
Clearly , if the no. of pumps will increase the no. of days will decrease
So , 15 , 7, x , 5 are inverse
So , 15 × 7 = 5x
x = (105)÷5
x = 21
So, the no. of extra pumps required is
= 21 - 15
= 6

Answer 2

there are 15 pumps which required 7 days; so for 5 days
15×7/5= 21