Question

If a diesel hose a can fill a car tank in 20 minutes and a diesel hose b can fill up the same tank in 15 minutes, how long will it take for the two hoses to fill the car tank together?

Answer 1

Answer:

Both will take 8 minutes 30 seconds to fill the tank.

Step-by-step explanation:

Solving it by the LCM method-

Time taken by hose A= 20 minutes

Time taken by hose B= 15 minutes

Taking their LCM, we get 60 ( total work)

Work done in unit time by A= 60/20 = 3

Work done in unit time by B= 60/15= 4

Hence, if both work together, time required to complete it= Total work/Total efficiency

= 60/7 = 8.5 minutes or 8 minutes 30 seconds