Topics
8. Probability & Statistics
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United States of AmericaAZ
7th Grade

8.05 Comparative inferences

Lesson
Practice

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

A stem-and-leaf plot displaying the data of weights of men. A stem-and-leaf plot is a way of organizing and displaying numerical data. In this plot, each data point is split into a stem (the leading digit or digits) and a leaf (the trailing digit). The stems are listed vertically, and the leaves corresponding to each stem are listed horizontally next to it. The weights of men presented in the stem and leaf plot are $68,71,73,72,75,72,73,73,73,73,82,79,82,81,77,77,75,77,81,77$68,71,73,72,75,72,73,73,73,73,82,79,82,81,77,77,75,77,81,77

A stem-and-leaf plot displaying the data of weights of women. A stem-and-leaf plot is a way of organizing and displaying numerical data. In this plot, each data point is split into a stem (the leading digit or digits) and a leaf (the trailing digit). The stems are listed vertically, and the leaves corresponding to each stem are listed horizontally next to it. The weights of women presented in the stem and leaf plot are $58,51,67,66,67,53,60,67,66,64,55,60,52,60,63,68,59,50,51,52$58,51,67,66,67,53,60,67,66,64,55,60,52,60,63,68,59,50,51,52
Click to view stem and leaf plots.
Key: 4 | 2 = 42 kg
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
3min

Isabelle thinks there may be a difference in the way males and females 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
1min

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

Easy
2min

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
2min
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Outcomes

7.SP.B.3

Informally assess the degree of visual overlap of two numerical data distributions with similar variabilities, measuring the difference between the centers by expressing it as a multiple of a measure of variability. For example, the mean height of players on the basketball team is 10 cm greater than the mean height of players on the soccer team, about twice the variability (mean absolute deviation) on either team; on a dot plot, the separation between the two distributions of heights is noticeable.

7.SP.B.4

Use measures of center and measures of variability for numerical data from random samples to draw informal comparative inferences about two populations. For example, decide whether the words in a chapter of a seventhgrade science book are generally longer than the words in a chapter of a fourth-grade science book.

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