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