Question 44

A can do a piece of work in 7 days of 9 hours each where as B can do the same work in 6 days of 7 hours each. How long will they take to do the work together, working $$8\frac{2}{5}$$ hours a day?

Solution

Work done by A and B in 1 hr per day = $$\frac{1}{63}+\frac{1}{42}=\frac{5}{126}$$

Number of hours they are required to work = $$\frac{42}{5}$$ hours

Number of days required = $$(\frac{1}{\frac{5}{126}})\div(\frac{42}{5})$$

= $$\frac{126}{5}\times\frac{5}{42}=3$$ days

=> Ans - (B)

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