Question

Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?

• A. 12 min
• B. 15 min
• C. 25 min
• D. 50 min
• E. 30 min

Answer 1

The correct option is A

12 min

Part filled by A in 1 minute =$\frac{1}{20}$
Part filled by B in 1 minute =$\frac{1}{30}$

Part filled by (A + B) in 1 minute = $(\frac{1}{20}+\frac{1}{30})=\frac{1}{12}$

$\therefore$ Both the pipes can fill the tank in 12 minutes.