1. A

2. B

3. C

4. D0% 0%0%0%

(over Lesson 8-1)

Which choice shows a line plot for the set of data?

A.

B.

C.

D.

Main Idea and Vocabulary

Key Concept: Mean

Example 1:Find the Mean

Key Concept: Median and Mode

Example 2:Find the Mean, Median, and Mode

Example 3:Test Example

Concept Summary: Mean, Median, and Mode

Example 4:Choose Mean, Median, or Mode

• measures of central tendency-mean, median, mode, range.

• Mean - average

• Median – middle number (in order from least to greatest

• Mode – number that occurs the most.

• Describe a set of data using mean, median, mode, and range (2.6.8A) (M7.E.2.1.1)

Find the Mean

ANIMALS The table below shows the number of species of animals found at 30 major zoos across the United States. Find the mean.

Source: The World Almanac

Find the Mean

sum of datanumber of data items

Answer: The mean number of species of animals is 436.47.

Add.

=436.4666 ...

Divide.

1. A

2. B

3. C

4. D

0% 0%0%0%

SLEEP The table below shows the results of a survey of 15 middle school students concerning the number of hours of sleep they typically get each night. Find the mean.

A. 4 hr

B. 7.13 hr

C. 7.5 hr

D. 8.25 hr

Find the Mean, Median, and Mode

OLYMPICS The table below shows the number of gold medals won by each country participating in the 2006 Winter Olympic games. Find the mean, median, and mode of the data.

Find the Mean, Median, and Mode

mode: number appearing most often, or 0

Answer: mean: 3.23; median: 2; mode: 0

1. A

2. B

3. C

4. D

0% 0%0%0%

A. mean: 0.78; median: 1.5; mode: 0

B. mean: 1.44; median: 1.5; mode: 5

C. mean: 1.44; median: 1; mode: 0

D. mean: 0.78; median: 1; mode: 0

PETS The table below shows the number of pets students in an art class at Green Hills Middle School have at home. Find the mean, median, and mode of the data.

The average weight in pounds of several breeds of dogs is listed below.

15, 45, 26, 55, 15, 30

If the average weight of the Golden Retriever, 70, is added to this list, which of the following statements would be true?

A The mode would increase.

B The median would decrease.

C The median would increase.

D The mean would decrease.

Read the Item You are asked to identify which statement would be true if the data value 70 was added to the data set.

Solve the Item Use number sense to eliminate possibilities.

The mode, 15, will remain unchanged since the new data value occurs only once. So, eliminate choice A.

Since the new data value is greater than each value in the data set, neither the mean nor the median will decrease. So, eliminate choices B and D.

Answer: So, the answer is C.

1. A

2. B

3. C

4. D

0% 0%0%0%

A. The mean would decrease.

B. The mode would decrease.

C. The median would stay the same.

D. The mean would increase.

If the average weight of a Chihuahua is added to the list in Example 3, which of the following statements would be true?

FIRST FAMILIES The line plot shows the number of children of United States presidents. Would the mean, median, or mode best represent the number of children?

Choose Mean, Median, or Mode

mode: 2

Answer: The mean, median, and mode are close, with values of 3.6, 3, and 2, respectively. Any of the three could be used to represent the data.

Choose Mean, Median, or Mode

1. A

2. B

3. C

4. D

0% 0%0%0%

A. mean

B. median

C. mode

D. any of the three

SIBLINGS The line plot below shows the number of siblings of each student in a particular classroom. Would the mean, median, or mode best represent the number of siblings?

REVIEW

1. The sizes of the bicycles owned by the students in Ms. Garcia’s class are as follows: 20, 24, 20, 26, 24, 24, 24, 26, 24, 29, 26, 24. What are the mean, median, and mode of the data?

2. The points scored in each game by Darby Middle School’s football team for 9 games are 21, 35, 14, 17, 28, 14, 7, 21, and 14. Find the mean, median, and mode.

3. Each team had the following numbers of wins: Eagles – 10, Hawks – 8, Zipps – 9, and Falcons – 11. Find the mean, median, and mode.

Mean = 24.25, median = 24, mode = 24

Mean = 19, median = 17, mode = 14

Mean = 9.5, median = 9.5, mode = none

End of the Lesson

Five-Minute Check (over Lesson 8–1)

Image Bank

Math Tools

Line Plots