Question

A is 3 times more efficient than B. Hence, he takes 60 days less in painting a room. In how many days, work will be completed, if A & B both work together ?

• A. $30$ days
• B. $45$ days
• C. $22\frac{1}{2}$ days
• D. $17\frac{1}{2}$ days

Answer 1

The correct option is C $22\frac{1}{2}$ days

A : B = x : 3x
Given that 3x - x = 60 = x = 30
A's efficiency = 30 and B's efficiency = 3 x 30 = 90
When A and B work together, they can complete the work in $\frac{30\times 90}{120}=22\frac{1}{2}$ days