Question

2 pipes P and Q can fill a tank in 18 hours and 22.5 hours respectively. If both are opened simultaneously, how much time will be taken to fill the tank?

• A. 17.5 hrs
• B. 12.5 hrs
• C. 20 hrs
• D. 10 hrs
• E. 15 hrs

Answer 1

The correct option is D

10 hrs

$\begin{array}{c}P=18Q=22.5\end{array}$

$\begin{array}{c}\frac{PQ}{P+Q}=\frac{18\times 22.5}{18+22.5}=10hours\end{array}$