Discussion Forum

Two pipes C and D can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?

Answer:

Explanation:

Part filled by $C$ in $1$ hour $=\frac{1}{36}$

Part filled by $D$ in $1$ hour $=\frac{1}{45}$

Part filled by $(C+D)$ in $1$ hour $=\left(\frac{1}{36}+\frac{1}{45}\right)$ $=\frac{9}{80}$ $=\frac{1}{20}$

Hence, both the pipes together will fill the tank in 20 hours.