To do a certain work, efficiencies of A and B are in the ratio of 7 : 5 , Working together, they can complete the work in 17 days. In how many days, will B alone complete 50% of the same work?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 21
Let the efficiency of A and B be 7x and 5x.
Total work = 12x × 35/2 = 210x.
50% of the work = 210x/2 = 105x.
Time taken by B to complete the task = 105x/5x = 21 days.