Sumit and Rajiv, working together, can do a job in 20 hours whereasSumit alone can do the same job in 25 hours. In how many hours can Rajiv alone do the job?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 100.
Let's denote the time taken by Rajiv alone to complete the job as R.
We can use the following formula for work and time problems:
(Work done by Sumit in 1 hour) + (Work done by Rajiv in 1 hour) = (Work done by both in 1 hour)
Translating this into an equation using the given information:
⇒ 1/25 + 1/R = 1/20
⇒ (R + 25) / (25R) = 1/20
⇒ 20(R + 25) = 25R
⇒ 20R + 500 = 25R
⇒ 500 = 5R
⇒ R = 100
Therefore, Rajiv alone can do the job in 100 hours.