C1, C2, and C3 can do a work alone in 10. 12 and 15 days respectively. All three of them began the work together but C2 left 2 days before the completion of the work. In how many days was the work completed?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. (14/3) days.
C1, C2, and C3 can do work alone in 10, 12, and 15 days respectively.
Let's assume the total work = LCM of 10, 12, and 15 = 60 unit
So, the efficiency of
C1 = 60/10 = 6 units per day
C2 = 60/12 = 5 units per day
C3 = 60/15 = 4 units per day
C2 left 2 days before the completion of the work
So, his 2 days work = 5 × 2 = 10 unit
Total time taken to finish the work = Total work/(efficiency of C1, C2 and C3)
So, the total time taken to finish the work = (60 + 10)/(6 + 5 + 4)
= 70/15
= 14/3 days