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:

5.15 kmph

4.14 kmph

4.25 kmph

4.4 kmph

Explanation:

As speed =$ \left(5 \times\dfrac{5}{18} \right) $m/sec=$ \dfrac{25}{18} $m/sec.

Time taken by A to cover 100 m =$ \left(100 \times\dfrac{18}{25} \right) $sec= 72 sec.

$\therefore$ Time taken by B to cover 92 m = (72 + 8) = 80 sec.

$\therefore$ Bs speed =$ \left(\dfrac{92}{80} \times\dfrac{18}{5} \right) $kmph= 4.14 kmph.