Problema Solution

A bathroom tub will fill in 15 minutes with both faucets open and the stopper in place. With both faucets closed and the stopper remove the tub will empty in 20 minutes. How long will it take for the tub to fill it both faucets are open and the stopper is removed?

Answer provided by our tutors

the rate of the both faucets open is 1/15 tubs per min


the rate of the stopper is 1/20 tubs per min


let t = the time (in minutes) needed for the tub to fill if both faucets are open and the stopper is removed


t(1/15 - 1/20) = 1


by solving we find


t = 60 min


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it will take 60 minutes or 1 hour for the tub to fill.