Number 8

3 marks · Normal

A runner completes a 10 km race in 40 minutes. Another runner completes a 5 km race in 20 minutes. Discuss whether both runners had the same average speed, showing your calculations and reasoning.

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Yes, both runners had the same average speed of 15 km/h.

Must show: calculation of both speeds, comparison, explanation

Also accept: Yes, they both ran at 15 km/h.

Common mistakes: Not converting minutes to hours; Comparing times instead of speeds

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Calculates speed for at least one runner: speed = distance/time, with correct conversions.

A1 · 1 mark · Finds both speeds as 15 km/h.

B1 · 1 mark · States that the runners had the same average speed, with justification.

Worked solution

Runner 1: 10 km in 40 min = 40/60 = 2/3 h

Average speed = 15 km/h.

Runner 2: 5 km in 20 min = 20/60 = 1/3 h

Average speed = 15 km/h.

Conclusion: Both runners had the same average speed.