7th Grade Math

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Measures of Central Tendency

PART A B C

Multi-Part

Lesson 1

GLE 0706.5.4

Use descriptive statistics to

summarize and compare

data. SPI 0706.5.3 Calculate

and interpret the mean,

median, upper-quartile,

lower-quartile, and

interquartile range of a set

of data. Also addresses

GLE 0706.1.7, GLE 0706.5.1.

Lesson 1B Measures of Central Tendency 491

Measures of Central Tendency

BICYCLES The sizes of students’ bicycles are

listed in the table.

1. Which number appears most often in the
   table?


2. Order the numbers from least to greatest.
   Which number(s) is in the middle?

Measures of central tendency are numbers that describe the center of

a data set. They are the mean, median, and mode.

Measures of Central Tendency

mean sum of the data divided by the number of items in

the set; commonly called the average

median middle number of the data ordered from least to greatest,

or the mean of the middle two numbers

mode number or numbers that occur most often

DVDS The numbers of DVDs Daily DVD Rentals

SMTWTHF S

55 34 35 34 57 78 106

rented during a week are

listed in the table. Find the

mean, median, and mode.

Mean __^55 +^34 +^35 +^34 7 +^57 +^78 +^106 = ^3997 or 57

Median 34, 34, 35, 55, 57, 78, 106 First, write the data in order.

Mode 34 It is the only value that occurs more than once.

The mean is 57 DVDs, the median is 55 DVDs, and the mode is

34 DVDs.

a. FOOTBALL The points scored in each game by Darby Middle

School’s football team are 21, 35, 14, 17, 28, 14, 7, 21, and 14.

Find the mean, median, and mode.

Main Idea

Determine and

describe how changes

in data values impact

measures of central

tendency.

Vocabulary

measures of central

tendency

mean

median

mode

V

m

Students’ Bicycle Sizes (in.)

20 24 20 26

24 24 24 26

24 29 26 24

490_497_C09_L1_895130.indd 491 1/11/10 9:31 AM