College Algebra

Question

An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 6 hours. If the main pump is started at 8 PM, when should the auxiliary pump be started so that the tankers empty by 11 PM?

Answer 1

The rate of the main pump is 1/4 tank/hr. The rate of the auxiliary pump is 1/6 tank/hr. We want to find the time, t, that the auxiliary pump goes so that the tank is empty in 3 hours (8 to 11)

(1/4 tank/hr)(3 hrs) + (1/6 tank/hr) * t hrs = 1 tank or 3/4 + t/6 = 1 and t = 6/4 = 1.5 hours.

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