Vikash and Ritesh working separately can do a piece of work in 12 and 15 days respectively If they w...........

Quantitative Aptitude (CDS) Time and work

Vikash and Ritesh working separately can do a piece of work in 12 and 15 days respectively. If they work for a day alternately, Vikash beginning, in how many days, the work will be completed?

13 days

14 days

15 days

16 days

Explanation:

(Vikash + Ritesh)'s 2 day's work = (1/12 +1/15 )
= 9/60
Work done in 5 pairs of days = (5×9/60)
= 45/60 = 3/4
Remaining work = (1 - 3/4) = 1/4
On 11th day, it is Vikash's turn. 1/12 work is done by him in 1 day.
1/4 work is done by him in ( 12×1/4) = 3 days
Total time taken = 10+3
= 13 days