A is thrice as efficient as B and hence completes a work in 40
days less than the number days taken by B. What will be
the number of days taken by both of them when working
together ?

Options

A. 22.5 days
B. 15 days
C. 20 days
D. 18 days

Answer

(b)

Explanation

Let efficiency of B is x
Days are inversaly proportional to efficiency.
According to question
`3x-x=40`
`2x =40`
`x=20`
Time taken by `A = x days = 20 days`
Time taken by `B=3x` days `= 3 xx 20= 60 ` days
Time taken by A and B togeter `= (20xx60)/(80 = 15` days