A runner's four lap times were 1 min 12.4 s, 1 min 10.9 s, 1 min 11.6 s and 1 min 9.5 s. What was the mean lap time?
Answer and explanation
Correct answer: B. 1 min 11.1 s
- Step 1: Convert to seconds: 72.4, 70.9, 71.6 and 69.5. Step 2. The total is 284.4 s. Step 3. 284.4 ÷ 4 = 71.1 s = 1 min 11.1 s. Answer: 1 min 11.1 s. Why not the others: 1 min 11.25 s: This is the median, the mean of the middle two laps, not the mean of all four. 1 min 11.6 s: This is the third lap time, not the mean. 1 min 12.4 s: This is the slowest lap time, not the mean.
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