Chain Rule Practice Test 2 with solutions

Here, work done = $\frac{1}{4}$ part
∴ Remaining work = $\left(1-\frac{1}{4}\right)$ = $\frac{3}{4}$
We have to find the number of additional men required, hence we shall compare each other item with the number of men.
Less hours per day, more men required (Indirect proportion)
More work, more men required (Direct proportion)
More days, less men required (Indirect proportion).

Since, $\frac{\mathit{x}}{400}$ = $\frac{\frac{3}{4}}{\frac{1}{4}}\times \frac{10}{20}\times \frac{9}{8}$
⇒ x = $\frac{3\times 10\times 9\times 400\times 4}{4\times 20\times 8}$ = 675
∴ Additional men = (675 – 400) = 275