Question

1 pump fill resovoir in 60 hrs other 80 hrs other 90 hrs when they are together how long to fill resovoir? Rsm

Answer 1

24.83 hours

Explanation:

Given that :

Let time taken by pumps be :

Pump A = 60 hours

Pump B = 80 hours

Pump C = 90 hours

Recall :

Rate = 1 / time taken

The rates of the pumps are :

Pump A rate = 1 / 60

Pump B rate = 1/80

Pump C rate = 1/90

Combined rate : 1/60 + 1/80 + 1/90

Combined rate = (12 + 9 + 8) / 720 = 29/720

Combined rate = 29/720

The time taken together will be :

1 / combined rate = 1/(29/720) = 720 / 29 = 24.827 hours