A bus covers the first 100 km at 50 km/h and the next 150 km at 75 km/h. Find the average speed for the whole journey.

medium 2 marks Class 4 · Mathematics · A Trip to Bhopal

Answer

62.5 km/h

The correct answer is 62.5 km/h — Average speed is total distance divided by total time: $V_{a v g} = \frac{D}{T} = \frac{250 km}{4 h} = 62.5 km/h$ .

Step-by-step solution

Compute time for first part: $t_{1} = \frac{100 km}{50 km/h} = 2 h$ .
Compute time for second part: $t_{2} = \frac{150 km}{75 km/h} = 2 h$ .
Add times to get total time: $T = t_{1} + t_{2} = 4 h$ .
Add distances to get total distance: $D = 100 + 150 = 250 km$ .
Average speed is total distance divided by total time: $V_{a v g} = \frac{D}{T} = \frac{250 km}{4 h} = 62.5 km/h$ .

Common mistake: Using weighted average of speeds instead of total distance/total time

Concept tested: Average speed calculation

Published 13 October 2026 · How this solution was prepared and checked

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