Ram can finish a piece of work in 10 days, while Shyam can do it in 15 days. If both work together, what time will they take to do the work?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 6 days
Work done in one day is the reciprocal of the days needed alone; working together, the one-day works add.
Ram does \(\frac{1}{10}\) and Shyam \(\frac{1}{15}\) of the work in a day
Together in one day: \(\displaystyle \frac{1}{10}+\frac{1}{15}=\frac{3+2}{30}=\frac{1}{6}\) of the work
So the whole work takes 6 days
Shortcut:
Together \(\displaystyle =\frac{xy}{x+y}=\frac{10\times15}{10+15}=\frac{150}{25}=6\) days