Question

Pipes A and B cab fill a tank in 10 hours and 15 hours respectively. Of both if them are openied together, in how much time can they fill?

Answer 1

Pipe A's 1hr work=1/10

pipe B's 1hr work =1/15

(A+B)'s 1hr work=1/10+1/15=

5/30=1/6

Now A and B can do it in 1÷1/6=6days.