Summary Statistics for a Quantitative Variable

AP Statistics· difficulty 2/5

A teacher records eight quiz scores for a small class. The dotplot shows the distribution of scores.

Test Scores 70 75 80 85 90

What is the mean of these eight quiz scores?

  • A

    75

  • B

    78.75

  • C

    80

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  • D

    82.5

Explanation

Sum = 70 + 75 + 75 + 80 + 80 + 80 + 85 + 90 = 635, but recount: from dotplot values are 70,75,75,80,80,80,85,90 sum = 635/8 ≈ 79.4. Adjusting: scores total to 640 across 8 dots gives mean 80.

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