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Question

If 'A' can complete half the work in 12 days and 'B' can complete half the work in 18 days, how long will they take to complete the entire task if they worked
together?

1. 30 days
2. 60 days
3. 7.2 days
4. 14.4 days
5. 21.6 days

Correct Answer
Choice (4). 14.4 days

Explanatory Answer

A can complete half the work in 12 days. So, A will complete the entire task in 24 days
B can complete half the work in 18 days. So, B will complete the entire task in 36 days.

Therefore, A will complete 1/24 th of the task in a day.
And B will complete 1/36 th of the task in a day.

Hence, if A and B work together, they will complete (1/24) + (1/36) of the task = (5/72) of the task in a day.
So, they will take 72/5 days = 14.4 days to complete the task.

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