Practice | Hashtable

1. 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

Solution:

\begin{aligned} 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} \end{aligned}

When B runs 90 m, C runs 72 m.
When B runs 100m, C run

(\frac{72}{90} \times 100) m = 80 m

∴ B can give C 20 m

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