Question

A swimming pool can be filled in 4 hours by 8 pumps of the same type. How many such pumps are required if the pool is to be filled in 223 hours?

Answer 1

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Proportion method

Let the required pumps to fill the swimming pool be x

Proportion : 4 : 2.75 : : 8 : x

We know that, Product of means = Product of extremes

Here extremes = 4, x ; means =2.75, 8

2.75×8=4×x

22=4x

22/4 = x

x = 11/2

x = 5.5

Therefore 5.5 pumps are required if the pool is to be filled in 11/4 hours.