Raju and Rajat working together take 5 days to complete a piece of work. If Raju alone can do this work in 7 days, how long would Rajat take to complete the same work?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 17.5 days.
Let the total work to be done (LCM of 5 and 7) be 35 units.
Efficiency of Raju and Rajat together = 35/5 = 7 units/day
Efficiency of Raju alone = 35/7 = 5 units/day
Efficiency of Rajat alone = 7 - 5 = 2 units/day
Time taken by Rajat alone = 35/2 = 17.5 days