Question Detail
A man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?
- \begin{aligned} 7\frac{1}{2}days \end{aligned}
- \begin{aligned} 6\frac{1}{2}days \end{aligned}
- \begin{aligned} 5\frac{1}{2}days \end{aligned}
- \begin{aligned} 4\frac{1}{2}days \end{aligned}
Answer: Option A
Explanation:
In this type of question, where we have one person work and together work done. Then we can easily get the other person work just by subtracting them. As,
Son's one day work =
\begin{aligned}
\left(\frac{1}{3}-\frac{1}{5} \right) \\
=\left(\frac{5-3}{15} \right) \\
= \frac{2}{15}
\end{aligned}
So son will do whole work in 15/2 days
which is =
\begin{aligned} 7\frac{1}{2}days \end{aligned}