Question

Tap a takes 6 minutes to fill a tank tabs B takes 9 minutes to fill the same tank pipe C can empty the tank in 15 minutes how long will it take to fill up the tank if the pipe is in use when both tabs a turned on

Answer 1

let t = time required to fill the tank in minutes

Let a full tank = 1;

Use plus for fill and minus for empty

+ - = 1

multiply equation the least common multiple, 90

90* + 90* - 90* = 90*1

Cancel the denominators

15t + 10t - 6t = 90

19t = 90

t = 90/19

t = 4.737 minutes