Mohan can do a piece of work in 7 days working 9 hours a day and Shyam can do the same work in 6 days working 7 hours a day. How long will they take to complete the job working together and 8 2/5 hours a day?

A3 days ✓ Correct

B4 days

C3 1/2 days

D5 days

Correct answer: (A) 3 days

Explanation

Together they finish in 3 days.

Mohan's total = 7 x 9 = 63 hours, Shyam's = 6 x 7 = 42 hours.

Combined one-hour work = 1/63 + 1/42 = 5/126.

Total time = 126/5 = 25.2 hours.

At 8 2/5 = 8.4 hours a day, 25.2 / 8.4 = 3 days.

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