Q141
ArithmeticTime & Work, Pipes & Cisterns
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete a work, how much time shall B take to do it alone?
- a.30 days
- b.35 days
- c.40 days
- d.45 days
Answer: (A) 30 days
A's rate = $\frac{1}{2} \div \frac{3}{4} = \frac{2}{3}$ of B's rate. Together they work at $\frac{5}{3}$ of B's rate, which equals $\frac{1}{18}$ per day, so B alone does $\frac{1}{30}$ per day. B needs 30 days; 45 days is A's time.