Question

8 pipes take 21 hrs to fill a drum. If 1 pipe is damaged, then find the total time taken to fill the drum ?

Answer 1

We know that
$\text{Number of pipes}\left(x\right)\propto \frac{1}{\text{Time taken}\left(y\right)}$
$\therefore \frac{x_1}{x_2}=\frac{y_2}{y_1}$
[1 mark]

Given,
$x_1=8pipes$
$y_1=21hours$
$x_2=8-1=7pipes$
$\text{and}{y}_2=\text{Time taken by 7 pipes}$
$y_2=\frac{8\times 21}{7}=24hours$
[2 mark]