Problem 19 · 2010 Math Kangaroo
Medium
Ratios, Rates & Proportions
distance-speed-timeproportion
Five students take part in a run. Their results are recorded in the graph opposite, showing the time taken (Zeit) and the distance covered (Strecke). Who had the greatest average speed?
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Answer: D — Doris
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Hint 1 of 2
Average speed is distance divided by time, the steepness of the line from the origin to that point.
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Hint 2 of 2
The fastest runner is the point making the steepest line up from 0.
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Approach: steepest distance-over-time point
- Speed is distance divided by time, the slope from the origin to each marked point.
- The point that is high up (large distance) yet far left (small time) has the steepest slope.
- That is Doris.
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