Question

A gardener uses pipes to water his garden from the tank. For his entire garden he uses 6 pipes to water and it takes him 1 hour 20 minutes to completely empty the tank. Now if he uses only 5 pipes to water his garden, how long it will take him to empty the tank?

• A. 1 hour 30 mins
• B. 1 hour 36 mins
• C. 1 hour 45 mins
• D. 1 hour 55 mins

Answer 1

The correct option is B

1 hour 36 mins

Let the time required be x.
$\begin{array}{ccc}No.ofpipes& 6& 5\\ Timetaken\left(min\right)& 80& X\end{array}$
$\therefore$ It is inverse variation.

$\frac{6}{5}$ = $\frac{x}{80}$
x =$\frac{6\times 80}{5}$ = 96 mins
x =1 hour 36 mins