Question

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?

• A. 2 days
• B. 3 days
• C. $3\frac{1}{7}$
• D. $4\frac{2}{5}$

Answer 1

Answer: (B)

3 days

Answer 2

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 $=(\frac{\frac{1}{5}}{126})$ ÷ $(\frac{42}{5})$

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

⇒ Ans - (B).The correct option is (B): 3 days