Topics
8. Probability & Statistics
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United States of AmericaUT
Grade 7

8.06 Comparative inferences

Lesson
Questions

Interactive practice questions

The weights of a group of men and women were recorded and presented in a stem and leaf plot as shown.

Men Women

Click to view stem and leaf plots.
Key: 4 | 2 = 42 kg
Two stem-and-leaf plots represent the weights of a group of men and women. The left plot is labeled "Men". The right plot is labeled "Women". In each plot, the left column is labeled "Stem" and the right column is labeled "Leaf", with values listed in rows next to each stem. On Men's stem and leaf plot, the weights are $68,71,72,72,73,73,73,73,73,75,75,77,77,77,77,79,81,81,82,82$68,71,72,72,73,73,73,73,73,75,75,77,77,77,77,79,81,81,82,82. On Women's stem and leaf plot, the weights are $50,51,51,52,52,53,55,58,59,60,60,60,63,64,66,66,67,67,67,68$50,51,51,52,52,53,55,58,59,60,60,60,63,64,66,66,67,67,67,68. A key is located below the plots and reads $4$4 | $2$2 = $42$42 kg, with the number $4$4 on the left of a vertical divider, the number $2$2 on the right, and $42$42 kg written to the right of the equals sign.
a

What is the mean weight of the group of men? Express your answer in decimal form.

b

What is the mean weight of the group of women? Express your answer in decimal form.

c

Which group is heavier?

Men

A

Women

B
Easy
3 min

Isabelle thinks there may be a difference in the way boys and girls compute certain puzzles.

She gave an equal number of boys and girls a knot to undo and recorded how long (in seconds) it took each of them. The results are presented in the table:

Easy
1 min

The following box-and-whisker plot shows the number of points scored by two basketball teams in each of their matches last season.

Easy
2 min

The following column graphs show the season results of two soccer groups, Group A and Group B, and the number of games (frequency) in which they scored a certain number of goals (scores).

Easy
2 min
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Outcomes

7.SP.3

Informally assess the degree of visual overlap of two numerical data distributions with similar variabilities, estimating the difference between the centers by expressing it as a multiple of a measure of variability.

7.SP.4

Use measures of center and measures of variability for numerical data from random samples to draw informal comparative inferences about two populations.

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