Practice Test Discussion

A train goes from delhi to kanpur and covers the whole distance with an average speed of 24 km/hr. The train covers half the distance with a speed of 25 km/hr. With what speed, did the train cover the remaining distance?

54 km/hr

45 km/hr

$23 \frac{1}{13}$ km/hr

46 km/hr

None of these

Explanation

According to the question

We know the formula

Average speed of the train= $\frac{2 AB}{A + B}$

where A=25 and B is to determine

$= 24 = \frac{2 \times 25 \times B}{25 + B} = 12 = \frac{25 B}{25 + B}$

= 300+12B=25B

=300=13B

(Or) B= $\frac{300}{13} = 23 \frac{1}{13} km / hr$

Hence, Option C is correct.

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