Measures of Center A1

Measures of Center & Range

Goal: Calculate the measures of center and range. ​

Measures of Center & Range

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​-Range

-Interquartile Range​

​Measures of Range

​Measures of Center

​-​Mean

-Median

-Mode​

-Quartiles​

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Multiple Choice

This measure of center is the middle of an ordered data set.

• Mean

• Median

• Mode

• Quartile

Multiple Choice

This measure of center is the average of a data set.

• Mean

• Median

• Mode

• Quartile

Multiple Choice

This measure of center is the most frequent value of a data set.

• Mean

• Median

• Mode

• Quartile

Multiple Choice

This measure of center is the median of the either the first half (Q1) or last half (Q3) of a data set.

• Mean

• Median

• Mode

• Quartile

​Mean

To calculate mean add the number in the data set, then divide by how many numbers are in the set.

Example: Find the mean: 4, 8, 5, 7, 6​

4 + 8 + 5 + 7 + 6 = 30​ and 30/5 = 6

So the mean is 6.​

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​Median

To calculate median order the numbers in the data set from least to greatest, then find the middle number, if two numbers are in the middle add them, then divide by 2.

Example: Find the median: 11, 7, 18, 9, 13, 14

Ordered: 7, 9, 11, 13​, 14, 18 Middle: 11 + 13 = 24/2 = 12

So the median is 12.​

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​Mode

To calculate mode find the number that appears the most in the data set, if no number is appears the most, no mode exists.

Example: Find the mode: 2, 4, 5, 4, 6, 3​

4 appears the most.

So the mode is 4.​

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​Quartiles (Q1 and Q3)

To calculate quartiles find the median of the first half of the data (Q1) and the median of the last half of the data (Q3).

Example: Find the quartiles: 2, 4, 5, 4, 6, 3​, 8

Ordered: 2, 3, 4, 4, 5, 6, 8

So Q1 is 3, and Q3 is 6.​

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Multiple Choice

What is the mean of: 32, 26, 18, 23, 26

• 18

• 26

• 25

• 14

Multiple Choice

What is the median of: 32, 26, 18, 23, 26

• 18

• 26

• 25

• 14

Multiple Choice

What is the mode of: 32, 26, 18, 23, 26

• 18

• 26

• 25

• 14

Multiple Choice

What is the Q1 of: 32, 26, 18, 23, 26, 27, 31

• 18

• 26

• 25

• 31

Multiple Choice

What is the Q13 of: 32, 26, 18, 23, 26, 27, 31

• 18

• 26

• 25

• 31

Range

To calculate range, subtract the largest number and smallest number in the data set.

Example: Find the range: 4, 8, 5, 7, 6​, 4, 9

Largest (9)​ and Smallest (4). 9 - 4 = 5

So the range is 5.​​

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​Interquartile Range (IQR)

To calculate interquartile range, find the median of the first half of the data (Q1) and the median of the last half of the data (Q3), and subtract Q3 - Q1.

Example: Find the IQR: 2, 4, 5, 4, 6, 3​, 8

Ordered: 2, 3, 4, 4, 5, 6, 8

Q1 is 3, and Q3 is 6.​ 6 - 3 = 3

So the IQR is 3.​

Subject | Subject

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Multiple Choice

What is the range of: 32, 26, 18, 23, 26, 27, 31

• 14

• 1

• 63

• 8

Multiple Choice

What is the IQR of: 32, 26, 18, 23, 26, 27, 31

• 14

• 1

• 63

• 8

Poll

How well did you understand measures of center and range?

• Entirely.

• Pretty good.

• Mostly understood.

• Not at all.