Question

A pipe of diameter ‘d' can empty a tank in 40 minutes then how much time will the pipe of diameter 2d take to empty the tank?/

Answer 1

pipe of diameter d can empty a tank in 40 minutes = 40d..........(1)

pipe of diameter 2d can empty a tank in x minutes = 2dx............(2)

equate (1) and (2)
2dx = 40d
x = 40/2
x = 20

so pipe of diameter 2d can empty a tank in 20 minutes