Question

Pramod can paint a wall red in 12 hours while Brijesh can white was the wall completely in 16 hours if Pramod and Brijesh work alternately for an hour each starting when the wall has just cement on it till when it is completely painted red how many hours will it take to paint the entire wall red

Answer 1

So in 1 hour :

Pramod paints = 1/12 of the wall red.

Brijesh paints = 1/16 of the wall white.

They work alternatively.

So in the first hour the 1/16 of the wall is painted white.

In the second hour 1/12 is painted red.

In two hours the wall painted red is :

1/12 - 1/16 = 1/48

So in 2 hrs, 1/48 of the wall is painted red.

In 2hrs = 1/48

?  = 1

48/1 × 2 = 96

= 96 hours