Question

A can complete a piece of work in 18 days. B is 20% more efficient than A. The number of days B takes to complete the same piece of work is?

• A. 12
• B. 15
• C. 10
• D. 9

Hint:

When one person is more efficient than another, use their efficiency multiplier to calculate the time taken.

Answer 1

The Correct Option is A

A completes the work in 18 days, so A's work rate is \( \frac{1}{18} \) of the work per day. B is 20% more efficient, so B's rate is \( 1.2 \times \frac{1}{18} = \frac{1.2}{18} \). The time taken by B to complete the work is the reciprocal of B's rate: \[ \text{Time taken by B} = \frac{1}{\frac{1.2}{18}} = \frac{18}{1.2} = 15 \text{ days}. \]