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A man covers half of a journey at $40$ km/hr and the other half at $60$ km/hr. Find his average speed for the whole journey.
A$45$ km/hr
B$48$ km/hr
C$50$ km/hr
D$52$ km/hr
Answer & Solution
Correct answer: B. $48$ km/hr
For equal distances, average speed is the harmonic mean: $\dfrac{2xy}{x+y} = \dfrac{2 \times 40 \times 60}{100} = \dfrac{4800}{100} = 48$ km/hr.
Option C ($50$, the arithmetic mean) applies only when *time* is split equally, not distance.
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