Suresh alone can do a work in 10 days working 1 hour a day. Shalu alone can do the same work in 2 days working 5 hours a day. How many hours do they need to work together in a day to complete the same work in 10 days?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 0.5 hours.
Time taken by Suresh to do the work = 10 × 1 = 10
Time taken by Shalu to do the work = 5 × 2 = 10
Total work (LCM of 10, 10) = 10
Work rate of Suresh = 10/10 = 1
Work rate of Shalu = 10/10 = 1
Total work rate of Suresh and Shalu = 1 + 1 = 2
To complete the work in 10 days, both will work together;
⇒ Time taken = (10 × 1 × 1)/(10 × 2)
⇒ 10/20 = 0.5