Question

Tick (✓) the correct answer:
6 pipes fill a tank in 120 minutes, then 5 pipes will fill it in
(a) 100 min
(b) 144 min
(c) 140 min
(d) 108 min

Answer 1

(b) 144 min
Let x min be the time taken by 5 pipes to fill the tank.

No. of pipes	6	5
Time (in min)	120	$x$

$$\begin{gathered} \mathrm{Now},6\times 120=5\times x \\ \Rightarrow x=144 \end{gathered}$$

Therefore, 5 pipes will take 144 min to fill the tank.