Question

In a 100 m race, A can give B 10 m and C 28 m. In the same race B can give C:

• A. 18 m
• B. 20 m
• C. 27 m
• D. 9 m

Answer 1

The correct option is B 20 m

A : B = 100 : 90.
A : C = 100 : 72.
B : C = $\frac{B}{A}\times \frac{A}{C}=\frac{90}{100}\times \frac{100}{72}=\frac{90}{72}$.
When B runs 90 m, C runs 72 m.
When B runs 100 m, C runs $\left(\begin{array}{c}\frac{72}{90}\times 100\end{array}\right)$ m = 80 m.
$\therefore$ B can give C 20 m.