A man can do a piece of work in 8 days and another man can do the same work in 10 days. How long should it take both of them working together but independently?

A6 days

B4 and 4/9 days ✓ Correct

C4 and 1/2 days

D5 and 1/5 days

Correct answer: (B) 4 and 4/9 days

Explanation

Working together they finish in 4 and 4/9 days.

One man does 1/8 of the work per day, the other 1/10.

Combined rate = 1/8 + 1/10 = 9/40 per day.

Time = reciprocal of the rate = 40/9.

40/9 = 4 and 4/9 days.

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