Ms. Drake 7th grade Math

Measures of Central Tendency

Lesson 4

Frequency Tables and Stem and Leaf Plots

Week by Week Essentials

http://mathlearnnc.sharpschool.com/cms/One.aspx?portalId=4507283&pageId=5149151

Go to: Resources for Mathematics: Grade 7 (2003

SCS)Week by Week Essentials

Measures of Central Tendency Vocabulary

Bar graphBox- and-Whisker PlotCircle GraphCumulative FrequencyDouble Bar GraphFirst QuartileFrequency Table

Measures of Central Tendency Vocabulary

HistogramLine GraphLower ExtremeMeanMedianModeNegative CorrelationNo correlation

Measures of Central Tendency Vocabulary

OutlierPopulationPositive correlationRandom SampleRangeSample

Measures of Central Tendency Vocabulary

Scatter PlotSecond QuartileSectorStem-and-Leaf PlotThird QuartileUpper Extreme

Frequency Tables

A table that lists items together according to the

number of times, or frequency, that the items

occur.

Frequency TableA frequency table is a way to organize data into categories,

groupsor intervals.

By including a cumulative frequency column in your table

you can keep a running total of the frequencies in each

interval.

Reading A Frequency Table

How many chickens owned per family

Frequency Cumulative Frequency

0-5 /// 36-11 ////// 9

12-17 //// 1318-23 // 15

How to Make a Frequency Table

Collect DataAverage Rainfall per Month in

Malaysia in millimeters:158, 201, 259, 292,

224,130,99,163, 218, 249, 259, 191

First determine the intervals, that is, how are you going to break up or group the data?

158, 201, 259, 292, 224,130,99,163, 218, 249, 259,

191The range is between

99 to 292Intervals must be even.

So intervals of 99?

0-99100-199200-299

Put data in the right interval158, 201, 259, 292,

224,130,99,163, 218, 249, 259, 191

Amount of Rainfall

Frequency Cumulative Frequency

0-99100-199200-299

Amount of Rainfall

Frequency Cumulative Frequency

0-99 / 1100-199 //// 5200-299 //// // 12

Does not give you exact data info

Let’s try this website together.

http://www.ixl.com/math/practice/grade-7-create-frequency-charts

A Stem and Leaf Plot can be used to show how often data values occur and how they

are distributed.

Minutes Doing HomeworkStems Leaves

2 1 2 6 9 3 2 2 5 6 8 4 3 5 5 5 7 8 5 6 4

The stems

are the tens

digits

There are no data values in

the 50’s

The leaves

are the

ones digits

Venezuela 21Columbia 35Ecuador 23

Peru 24Bolivia 11

Chile 5Argentina 20

Uruguay 6Paraguay 13

Brazil 64French Guiana 6

Suriname 5Guyana 6

Numbers of Endangered Species

21, 35, 23, 24, 11, 5, 20, 6, 13, 64, 6, 5, 6

Endangered

Species

5 5 6 6 6 1

1 3

2

0 1 3 4

3

5

4 5 6

4

Stem Plots

Here is a great website to help you practice how to read and interpret stem and leaf

plots.

http://www.shodor.org/interactivate/activities/StemAndLeafPlotter

/

Try this on your own.

http://www.glencoe.com/sec/math/studytools/cgi-bin/msgQuiz.php4?isbn=0-02-833050-1&chapter=2&lesson=1