Question

Two pipes can fill a tank in 20 minutes,end 30 minutes respectively. If both the pipes are opened simultaneously then the lank will he filled 

A. 10 minutes 

B. 12 minutes 

C. 15 minutes 

D. 25 minutes

Answer 1

Number of minutes Pipe A requires to fill an empty tank : 20 minutes 

Number of minutes Pipe B requires to fill an empty tank : 30 minutes

Amount of water filled by Pipe A in empty tank in one minute: \(\frac{1}{20}\)

Amount of water filled by Pipe B in one minute: \(\frac{1}{30}\)

Amount of water filled by Pipe A and Pipe B together in one minute: 

\(\frac{1}{20}+\frac{1}{30}=\frac{5}{60}=\frac{1}{12}\)

∴ They can fill the tank together in 12 minutes.