Q:

priority questionThe dot plots below show the test scores of sixth- and seventh-grade students: Dot plot for Grade 6 shows 6 dots on score 70, 4 dots on score 80, 6 dots on score 90, and 4 dots on score 100. Dot plot for Grade 7 shows 5 dots on score 50, 7 dots on score 60, 4 dots on score 70, and 4 dots on score 80. Based on visual inspection of the dot plots, which grade, if any, appears to have the higher mean score? Grade 6 Grade 7 Both groups show about the same mean score. No conclusion about mean score can be made from the data.

Accepted Solution

A:
Sixth grade:
7 | x x x x x x
8 | x x x x
9 |x x x x x x
A | x x x x . . . . . . . . where "A" is used to represent 10 tens (100)

7th grade:
5 | x x x x x
6 | x x x x x x x
7 | x x x x
8 | x x x x

The range (low, high) and median of the 6th grade scores are all higher than those of the 7th grade scores.

Based on visual inspection, Grade 6 appears to have the higher mean score.