A can do a certain work in 12 days. B is 60% more efficient than A. How many days does B alone take to do the same work?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 7.5 days
For the same work, the time taken is inversely proportional to efficiency: a person who does more work each day needs fewer days.
B is 60% more efficient, so B’s efficiency : A’s efficiency \(=160:100=8:5\)
The times are in the inverse ratio, B : A \(=5:8\)
B’s time \(\displaystyle =12\times\frac{5}{8}=\) 7.5 days