Pipes A and B can fill a storage tank in 8 hours and 12 hours, respectively. With the tank empty, pipe A was turned on at noon, and then pipe B was turned on at 1:30 P.M. At what time was the tank full?

Question

Pipes A and B can fill a storage tank in 8 hours and 12 hours, respectively.  With the tank empty, pipe A was turned on at noon, and then pipe B was turned on at 1:30 P.M.  At what time was the tank full?

Damon · Answer

A does (1/8) tank/hr B does (1/12) tank/hr how long to fill (1/8)t + (1/12)(t-1.5) = 1 tank full 3 t + 2t - 3 = 24 5 t = 27 t = 27/5 = 5 2/5 hr 2/5 * 60 = 24 min so 5:24 pm