Swapnil can build a sofa in 16 dyas. Working together with Revathi he can finish the work in 128/17 days. Find the number of days taken by Revathi to complete the work if she works alone.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 128/9 days.
Swapnil can build a sofa = 16 days
Swapnil and Revathi can finish the work together = 128/17 days
Swapnil’s work rate = 1/16
Combined work rate = 1/(128/17) = 17/128
Let Revathi's work rate = x
⇒ Swapnil’s work rate + Revathi’s work rate = Combined work rate
⇒ 1/16 + x = 17/128
⇒ x = 17/128 - 1/16 = (17 - 8)/128 = 9/128
Number of days = 1/x = 1/(9/128) = 128/9 days