A and B take part in a 100 m race. A runs at 5 km/h. If A

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RRB TC CC Exam (Bangalore) 2007 click here to view all questions

A and B take part in a 100 m race. A runs at 5 km/h. If A starts after B runs 8 m,and wins the race by 8 seconds, the speed of B is

A4.15 km/ h

B4.14 km/ h

C4.25 km/ h

D4.41 km/ h

Nithin K ? Nov 26 '2016 at 19:24

Answer is : 4.14 km/ h

Explanation:

\(\text{A's Speed = } \big(5 \times \frac{5}{18}\big)m/s  \)

\(= 25 \text{ m/s}\)

\(\text{Time taken by A to cover 100 m = }100 \times \frac{18}{25} sec \)

=72 sec

\(\text{Time taken by B to cover 92 m = } 72+8\)

=80 sec

\(\therefore \text { B's Speed }= \big( \frac{92}{80} \times \frac{18}{5} \big) kmph\)

=4.14 kmph

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Answer is : 4.14 km/ h Explanation: \(\text{A's Speed = } \big(5 \times \frac{5}{18}\big)m/s  \) \(= 25 \text{ m/s}\) \(\text{Time taken by A to cover 100 m = }100 \times \frac{18}{25} sec \) =72 sec \(\text{Time taken by B to cover 92 m = } 72+8\) =80 sec \(\therefore \text { B's Speed }= \big( \frac{92}{80} \times \frac{18}{5} \big) kmph\) =4.14 kmph Nithin K ? answered Nov 26 '2016 at 19:24 All Comments

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