Practice | Hashtable

1. A and B take part in 100 m race. A runs at 5 kmph. A gives B a start of 8 m and still beats him by 8 seconds. The speed of B is:

A. 5.15 kmph

B. 4.14 kmph

C. 4.25 kmph

D. 4.4 kmph

Solution:

\begin{aligned} A's speed = (5 \times \frac{5}{18}) m/sec \\ = \frac{25}{18} m/sec \\ Time taken by A to cover 100 m \\ = (100 \times \frac{18}{25}) \sec \\ = 72 \sec \\ ∴ Time taken by B to cover 92 m \\ = (72 + 8) = 80 \sec \\ ∴ B's speed = (\frac{92}{80} \times \frac{18}{5}) kmph \\ = 4.14 kmph \end{aligned}

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