Q167
ArithmeticTime & Work, Pipes & Cisterns
Bulu and Tathagata can do a work separately in 20 days and 30 days respectively. After working 7 days both of them left away. Then Anita came and completed rest of the work done alone in 10 days. How many days Anita will take to complete the work alone?
- a.20 days
- b.25 days
- c.24 days
- d.None of the above
Answer: (C) 24 days
Together Bulu and Tathagata do $\frac{1}{20} + \frac{1}{30} = \frac{1}{12}$ a day, so in 7 days they finish $\frac{7}{12}$. Anita does the remaining $\frac{5}{12}$ in 10 days, so the whole work takes her $10 \times \frac{12}{5} = 24$ days.