Problema Solution
The inlet pipe of an oil tank can fill the tank in 1 hour 30 min. The outlet pipe can empty the tank in 1 hour. How long will it take to empty a full tank if both pipes are open?
Answer provided by our tutors
The inlet pipe of an oil tank can fill the tank in 1 hour 30 min = 1.5 hours.
1/1.5 pool per hour is the rate of the inlet pipe
1 pool per hour is the rate of the outlet pipe
t = the time needed to empty a full tank
1 + t/1.5 - t*1 = 0
........
........
t = 3 hr
It will take 3 hours to empty a full tank with both pipes open.