Question

If 12 girls can complete a piece of work in 4 days, then find the time required to complete the same work by 4 girls.

• A. 4
• B. 8
• C. 12
• D. 16

Answer 1

The correct option is C 12

The number of girls (N) employed to complete a piece of work is inversely proportional to the number of days (D).

$\Rightarrow N\propto \frac{1}{D}$

Let the constant of variation be k.
$\Rightarrow N=\frac{k}{D}$
$\Rightarrow ND=k$
Given, when N = 12 girls , D = 4 days.
So, $k=ND=\left(12\right)\left(4\right)=48$
$\Rightarrow N=\frac{48}{D}$
Hence, the time required (D) to complete the same work by 4 girls $=\frac{48}{N}=\frac{48}{4}=12\text{days}.$