Five men are working to complete a work in 15 days. After five days 10 women are accompanied by them to complete the work in next 5 days. If the work is to be done by women only, then in how many days could the work be over if 10 women have started it ?

Answer: Option C

5 men's 15 day's work = 5 men's 10 day's work + 10 women's 5 day's work
⇒ 5 men's 5 day's work = 5 women's 5 day's work
⇒ 10 women's 5 day's work
$$\begin{array}{rl}& =\left(\frac{1}{15}\times 5\right)\\ & =\frac{1}{3}\end{array}$$
⇒ 10 women's 1 day's work = $$\frac{1}{15}$$
∴ 10 women can complete the work in 15 days.