4.8:mean, median, mode & range measures of central tendency

4.8:Mean, Median, Mode 4.8:Mean, Median, Mode & Range& Range

Measures of Central Tendency

Definition

MeanMeanMeansMeans

AverageAverage

How to Find the Mean of a Group of Numbers

• Step 1 – Add all the numbers.

8, 10, 12, 18, 22, 26

8+10+12+18+22+26 = 96

How to Find the Mean of a Group of Numbers

• Step 2 – Divide the sum by the number of addends.

8, 10, 12, 18, 22, 26

8+10+12+18+22+26 = 96 How many addends are there?

How to Find the Mean of a Group of Numbers

• Step 2 – Divide the sum by the number of addends.

6)96 sum# of addends1

636

6

63

How to Find the Mean of a Group of Numbers

The mean or average of these numbers is 16.

8, 10, 12, 18, 22, 26

Ex1 :What is the mean of these numbers?

7, 10, 15

10.6

Ex 2: What is the mean of these numbers?

2, 9, 14, 27

13

Definition

MeMeddianianis in theis in theMiMiddddlele

How to Find the Median in a Group of Numbers

• Step 1 – Arrange the numbers in order from least to greatest.

21, 18, 24, 19, 27

18, 19, 21, 24, 27

How to Find the Median in a Group of Numbers

• Step 2 – Find the middle number.

21, 18, 24, 19, 27

18, 19, 21, 24, 27

How to Find the Median in a Group of Numbers

• Step 2 – Find the middle number.

18, 19, 21, 24, 27

This is your median number.

How to Find the Median in a Group of Numbers

• Step 3 – If there are two middle numbers, find the mean of these two numbers.

18, 19, 21, 25, 27, 28

How to Find the Median in a Group of Numbers

• Step 3 – If there are two middle numbers, find the mean of these two numbers.

21+ 25 = 46

2) 46 23 median

Ex 4: What is the median of these numbers?

16, 10, 7

10

7, 10, 16

Ex 6: What is the median of these numbers?

31, 7, 2, 12, 14, 19

132, 7, 12, 14, 19, 31

12 + 14 = 26 2) 26

Definition

ModeModeis the mostis the most

PopularPopular

How to Find the Mode in a Group of Numbers

• Step 1 – Arrange the numbers in order from least to greatest.

21, 18, 24, 19, 18

18, 18, 19, 21, 24

How to Find the Mode in a Group of Numbers

• Step 2 – Find the number that is repeated the most.

21, 18, 24, 19, 18

18, 18, 19, 21, 24

Ex 7: number is the mode?

29, 8, 4, 8, 19

84, 8, 8, 19, 29

Ex 8: Which number is the mode?

1, 2, 2, 9, 9, 4, 9, 10

9

1, 2, 2, 4, 9, 9, 9, 10

What is an Outlier?

• A data item that is far apart from the rest of the data items

• Which will an outlier affect the most: the mean, median or mode? (Hint: Think of class test scores

• Sometimes you can throw out the outlier to find a more accurate mean

You need a mean test score of 90 points. So far, you have taken 5

tests: 94, 84, 90, 88, and 91. What is the minimum score you need on

your next test to get an A.94 84 90 88 91

906

x

44790

6

x 540 447 x

93x

Video

• http://www.youtube.com/watch?v=5C9LBF3b65s

Homework

• Page 205 (1-20) all

Copyright © 2000 by Monica Yuskaitis