A and B can complete a piece of work in 8 days and 16 days respectively. If A and B work on alternate days, starting with B, in how many days the work will be completed?
Show answer & explanation
Correct answer: D
Explanation
The Correct answer is option 4 i.e. 11.
A can complete a piece of work = 8 days
B can complete a piece of work = 16 days
Total work = LCM of 8 and 16 = 16 unit
Efficiency = Total work/Total time
So, efficiency of A = 16/8 = 2 unit per day, B = 16/16 = 1 unit per day
They work on alternate days and started with B
Their work
2 days = 1 + 2 = 3 unit
10 days = 3 × 5 = 15 unit
Now its B turn, Remaining work = 16 - 15 = 1 unit
It done by B = 1/1 = 1 day
Total days = 10 + 1 = 11 days