IXL | Compare populations using line plots

The line plots show the heights of a sample of 8 girls and 8 boys in seventh grade.

Girls

Height (inches)

Boys

Height (inches)

Complete the table. Write your answers as whole numbers or decimals rounded to the nearest tenth.

	Mean	Range
Girls
Boys	62	8

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Learn with an example

question

Todd is a biologist. He studies bald eagles in a national park. Todd recorded the wingspans for a sample of male bald eagles and a sample of female bald eagles. The results are shown in the line plots.

Males

1.5

1.7

1.9

2.1

2.3

2.5

Wingspan (meters)

Females

1.5

1.7

1.9

2.1

2.3

2.5

Wingspan (meters)

Complete the table. Write your answers as whole numbers or decimals rounded to the nearest tenth.

	Mean	Range
Males		0.5
Females	2.2

key idea

The mean is the average value of the data set. It describes the center of the data set.

The range is the difference between the greatest number and the least number in the data set. It describes the variability of the data set.

solution

First, find the mean wingspan for the sample of male bald eagles. You can create a frequency table for the line plot to help.

Wingspans	Frequency
1.5	1
1.6	2
1.7	1
1.8	1
1.9	2
2	3

The mean is the average of all 10 data values. To find the average, you can multiply each value by the number of times it occurs, add these products, then divide by the total number of values.

1.5

1.6

1.7

1.8

1.9

1.8

The mean wingspan for the sample of male bald eagles is 1.8

meters.

Next, find the range of the wingspans for the sample of female bald eagles. The longest wingspan was 2.5, and the shortest wingspan was 1.8. Subtract to find the range.

2.5

–

1.8

0.7

The range of the wingspans for the sample of female bald eagles is 0.7

meters.

Finally, use these values to complete the table.

	Mean	Range
Males	1.8	0.5
Females	2.2	0.7

$Confetti$

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Find the mean and range

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