Question

12 men working 8 hours a day complete a work in 10 days. How long would 16 men working 7 $\frac{1}{2}$ hours a day take to complete the same work ?

Answer 1

Let the work completed in x days.
$\begin{array}{ccc}\text{Mens}& \text{Hours}& \text{Days}\\ 12& 8& 10\\ 16& \frac{15}{2}& x\end{array}$
More men less time , Less men more time. Thus it is inverse variation
$12:16::\frac{15}{2}\times x:8\times 10$
$\Rightarrow x=\frac{10\times 12\times 8\times 2}{16\times 15}=8$
$\Rightarrow$16 men will complete the same work in 8 days.