Question

an empty 50 gallon is filled with water by faucet with a rate 4 gallon per min while it can be drain by a faucet at the bottom of the drum by half a gallon per minute . how long will it take the faucet to fill the drum up to brim if at the same time the faucet at the bottom is open`

Answer 1

net inflow is 4 - 1/2 = 7/2 gal/min

So, it takes 50/(7/2) = 14.3 min to fill

Answer 2

tnx