Question

8 pumps can fill a tank in 1 hour 30 minutes. How long will it take it take if only 6 pumps of the same type are used?​

Answer 1

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Let the desired time to fill the tank be x minutes. Thus, we have the following table:

• Number of pumps 8 and 6
• Time (in minutes) 90 x

Lesser the number of pumps, more will the time required by it to fill the tank.

So, this is a case of inverse proportion

Hence,

$\sf \: 90×8=x×6 \: \: \: \: \: \: \: \: \: (x_1y_1=x_2 y_2 ) \\ \\ \sf \implies\frac{90 \times 8}{6} =x$

or x=120 minutes

Thus, time taken to fill the tank by 6 pumps is 120 minutes or 2 hours.