Pipe A can fill the tank in 8 hours and pipe B can fill it in 12 hours. If pipe A is opened at 7:00 am and pipe B is opened at 9:00 am, then at what time will the tank be full?

Solution (By Examveda Team)

A opened 2 hours early to B
In 2 hours A can do 3 × 2 = 6 unit work
Remaining work = 24 - 6 = 18
A + B can do it in $$ \to \frac{{18}}{5}$$
= $$3\frac{3}{5}{\text{ hrs}}$$
= 3 hrs 36 min
∴ Tank will be full in 9 am + 3 hrs 36 min = 12 : 36 pm