A can do a task in 18 days, and B in 9 days. After working together for 4 days, A leaves. How many more days will B take to complete the remaining work?
Show answer & explanation
Correct answer: D
Explanation
A's 1-day work efficiency = 1/18
B's 1-day work efficiency = 1/9
Combined 1-day work efficiency of both = 1/18 + 1/9
= 1/18 + 2/18
= 3/18
= 1/6
Work done in 4 days = 4 × 1/6
= 2/3
Remaining work = 1 - 2/3
= 1/3
Now, B alone will complete the remaining 1/3 of the work.
B's 1-day work efficiency = 1/9
Therefore, time required = (1/3) ÷ (1/9)
= (1/3) × 9
= 3 days