Riya alone can complete a piece of work in 6 days while Siya alone can do the same work in 9 days. If they both work together, then how many days will be required to finish the work?
Answer & explanation
Correct answer: option 2
Riya : Siya
Time taken 6 : 9
Efficiency 3 : 2
Total work = LCM of 6, 9 = 18
Total efficiency = 3 + 2 = 5
Time taken to complete the work together = $\frac{total\; work}{efficiency}$
= $\frac{18}{5}$ days