Question

Two pipe a and b.a empty tank fill in 15 min and 20 min respectevely.both pipes are open in a tank simetounosly and after 4 min.pipe a. has closed then find out the total time of filling the tank.

Answer 1

The part of the tank filled in 4 mis = 4/15 +4/20 = 28/60 = 7/15

Now the remains part 8/15 will be filled by by B alone = 8/15 ×20 = 32/3


Total time = 4 + 32/3 = 44/3 answwer