Correct Answer: 7-(5)

Solution: (5) Work done by 15 men in 9 days $=W_{2}$ (let)

$\therefore \frac{M_{1} D_{1}}{W_{1}}=\frac{M_{2} D_{2}}{W_{2}}$

$\Rightarrow \frac{18 \times 30}{1}=\frac{15 \times 9}{W_{2}}$

$\Rightarrow 18 \times 30 \times W_{2}=15 \times 9$

$\Rightarrow W_{2}=\frac{15 \times 9}{18 \times 30}=\frac{1}{4}$

Remaining work $=1-\frac{1}{4}=\frac{3}{4}$

Again, 16 women complete the project in 36 days.

$\therefore \frac{M_{1} D_{1}}{W_{1}}=\frac{M_{2} D_{2}}{W_{2}}$

$\Rightarrow \frac{16 \times 36}{1}=\frac{18 \times D_{2}}{\frac{3}{4}}$

$\Rightarrow 18 \times D_{2}=\frac{3}{4} \times 16 \times 36$ $=27 \times 16$

$\Rightarrow D_{2}=\frac{27 \times 16}{18}=24$ days