Question

Two pipes can fill a tank In 20 minutes and 30 minutes respectively. If both the pipes are opened simultaneously, then the tank will be filled in

(a) 10 minutes

(b) 12 rendes

(c) 15 minutes

(d) 25 minutes

Answer 1

First pipe 1 minutes work $=\frac{1}{20}$

Second pipe 1 minutes work $=\frac{1}{30}$

$\therefore$ Both's 1 minute work $=\frac{1}{20}+\frac{1}{30}$

$=\frac{3+2}{60}=\frac{5}{60}=\frac{1}{12}$

$\therefore$ Both will do the work in =12 minutes