15 men and 25 women together can complete a work in 5 days. It takes 90 days for one man alone to complete the same work. How many days will be required for one woman alone to complete the same work?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 750
Work done in a day adds up over the workers. Find what the 15 men do in a day; the rest of the day’s work is done by the 25 women.
Work of 15 men and 25 women in a day \(=\displaystyle\frac{1}{5}\)
Work of 1 man in a day \(=\displaystyle\frac{1}{90}\), so 15 men do \(\displaystyle\frac{15}{90}=\frac{1}{6}\)
Work of 25 women in a day \(=\displaystyle\frac{1}{5}-\frac{1}{6}=\frac{1}{30}\)
Work of 1 woman in a day \(=\displaystyle\frac{1}{30\times25}=\frac{1}{750}\)
So one woman alone needs 750 days.