Lesson 12-2 Pages 612-616

Measures of Variation

What you will learn!1. How to find measures of variation.

2. How to use measures of variation to interpret and compare data.

Measures of variationMeasures of variationQuartilesQuartilesLower quartileLower quartileUpper quartileUpper quartileInterquartile rangeInterquartile range

Measures of VariationMeasures of Variation

TermTerm DefinitionDefinition

RangeRangeThe difference between the The difference between the least value and greatest value least value and greatest value of the set.of the set.

MedianMedian The value that separates the The value that separates the data set in half.data set in half.

Lower Lower QuartileQuartile

The median of the lower half The median of the lower half of the set of data.of the set of data.

Upper Upper QuartileQuartile

The median of the upper half The median of the upper half of the set of data.of the set of data.

Interquartile Interquartile rangerange

The difference between the The difference between the upper quartile and the lower upper quartile and the lower quartile.quartile.

Example 1:

Find the range of each set data.

A.A. 7979,,

4242,,

3838,,

5151,,

6363,,

9191

91 – 38 = 91 – 38 = 5353

Example 1b:

Find the range of each set data.

59 – 33 = 59 – 33 = 2626

StemStem LeafLeaf33 3 3 5 7 7 83 3 5 7 7 844 0 3 3 4 90 3 3 4 955 4 94 9

4│3 = 43

Example 2:

Find the interquartile range.

3838,,

4040,,

3232,,

3434,,

3636,,

4545,,

33333232 3333 3434 3636 3838 4040 4545

MedianLQ UQ

40 – 33 = 40 – 33 = 77

Example 2b:

Find the interquartile range.2,2, 27,27, 17,17, 14,14, 14,14, 22,22, 15,15, 32,32, 2424

,,2525

Median 19.5

LQ UQ

25 – 14 = 25 – 14 = 1111

22 1414 1414 1515 1717 2222 2424 2525 2727 3232

Example 3: The urban land in certain western and eastern states is listed below as the percent of each state’s total land.

Western Western StatesStates

Eastern Eastern StatesStates

1 1 1 1 1 0 01 1 1 1 1 0 0 003 2 2 2 1 1 13 2 2 2 1 1 1

003 3 4 5 6 6 3 3 4 5 6 6 88

5 4 45 4 400

8 9 9 9 9 9 8 9 9 9 9 9 99

11 1 3 3 4 4 51 3 3 4 4 522 3 6 73 6 733 55

1│3 = 13%4│0 = 4%

What is the median percent of urban land use for each region?

Western Western StatesStates

Eastern Eastern StatesStates

1 1 1 1 1 0 01 1 1 1 1 0 0 003 2 2 2 1 1 13 2 2 2 1 1 1

003 3 4 5 6 6 3 3 4 5 6 6 88

5 4 45 4 400

8 9 9 9 9 9 8 9 9 9 9 9 99

11 1 3 3 4 4 51 3 3 4 4 522 3 6 73 6 733 55

1│3 = 13%4│0 = 4%

1% 9%

Compare the range for each set of data.

1│3 = 13%

Western Western StatesStates

Eastern Eastern StatesStates

1 1 1 1 1 0 01 1 1 1 1 0 0 003 2 2 2 1 1 13 2 2 2 1 1 1

003 3 4 5 6 6 3 3 4 5 6 6 88

5 4 45 4 400

8 9 9 9 9 9 8 9 9 9 9 9 99

11 1 3 3 4 4 51 3 3 4 4 522 3 6 73 6 733 55

5% - 0% = 5%

35% - 3% = 32%

4│0 = 4%

Page 614

Guided Practice

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study examples!

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Homework: Pages 615-616

#’s 9-18, 23-33

Lesson Check 12-2

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Lesson 12-2