A and B can do a piece of work in 12 days and 18 days, respectively. They work on alternate days, starting with A. How many days will it take to complete the work?
Show answer & explanation
Correct answer: B
Explanation
Given:
A = 12 days, B = 18 days
A's rate = 1/12
B's rate = 1/18
Work done in 2 days = 1/12 + 1/18 = (3 + 2)/36 = 5/36
1 cycle (2 days) = 5/36
7 cycles (14 days) ⇒ 35/36 of the work
Remaining work = 1/36
On the next day, A will work
A's work in 1 day = 1/12
Time required = (1/36) ÷ (1/12) = 1/3 day
Total time = 14 + 1/3 = 14⅓ days