Measures of Central TendencyAlgebra 1(B)Statistics

Today’s Schedule• Class Attendance / Announcements• Multiple Choice Warm-Up• Homework Check / Questions• Measures of Central Tendency Notes / Practice• Brain Break• Mean, Median, and Mode Numbers Game• Exit Slip• Begin Homework

Multiple Choice Warm-UpDo your best on the following problems. Remember:

try to eliminate answers you know are not correct!

1.

2.

3.

Homework Check / Questions

pgs. 371, 373 #9, 13-16, 34

Objectives1. Understand and apply the measures of

central tendency2. Recognize situations in which one

measure of central tendency is more reliable than another

Vocabulary: measures of central tendency, mean, median, mode

What is the Mean?Mean: the “average” of a set of data found

by…1. Adding the data in the set and…2. Dividing that sum by the number of

elements in the set.Example:Find the mean of the collection of numbers:6, 5, 7, 5, 3, 4

6 5 7 5 3 46

306

5

Finding the MeanA football team had offensive drives of 43, 42,

45, 44, 45, and 48 yards. Find the mean offensive drive for the team.

44.5 yard

s

Finding the MeanThe heights of the players on Oswego High

School’s basketball team are 72”, 74”, 70”, 78”, 75”, and 70”. Find the mean height. Round your answer to the nearest tenth.

73.2 inche

s

Finding the MeanThe high temperatures for a 7-day week during

December in Oswego were 29°, 31°, 28°, 32°, 29°, 27°, and 62°. Find the mean high temperature for the week.

34°

Is 34° a good representation of a typical week in Oswego in December. Why or why not?• Discuss this question with your partner for one minute• You will be asked to support your reasoning

What is the Median?Median: the middle number of a set of data

when the numbers are arranged in numerical order.

Example:Find the median of the collection of numbers:

2, 16, 9, 10, 20, 5, 1, 10, 23

1, 2, 5, 9, 10, 10, 16, 20, 2310

Finding the MedianThe rainfall in the month of April in Oswego

over the past 5 years has been 3.6”, 2.92”, 3.62”, 3.2”, and 3.37”. Find the median amount of rainfall in April.

3.37 inche

s

Finding the MedianFind the median of the collection of numbers:

13.5

17, 20, 2, 8, 17, 14, 20, 13, 5, 10

What should we do if there is no middle number?

Find the average of the two middle numbers!

What is the Mode?Mode: the number that occurs most often in a

set of data.Hint: It will help to arrange numbers in numerical

order.

Example:Find the mode of the collection of numbers:

1, 12, 4, 5, 4, 8, 2

1, 2, 4, 4, 5, 8, 121, 2, 4, 4, 5, 8, 12

Finding the ModeYour homework scores in math this semester

have been 89%, 100%, 96%, 77%, 80%, 96%, 88%, and 83%. What is the mode of your homework scores?

96%

Finding the ModeFind the mode of the collection of numbers:

No mod

e

Find the mode of the collection of numbers:

70, 55, 60, 28, 55, 68, 70, 40

55 and 70

12, 8, 15, 17, 5, 3, 11, 9

We call a set of data bimodal if it has two modes.

Brain BreakTake 2-3 minutes to get up, stretch out, talk to

a neighbor, or try the following rebus puzzles…

Skate on thin ice

Up for grabs

Mean, Median, Mode Numbers GameInstructions:

1. You will be divided into groups of 4. When you are sitting with your group, turn your desks to face each other.

2. Determine an order (who will go first, second, third, and fourth).3. There will be two piles of cards: a numbers pile and a M-M-M

(mean-median-mode) pile.4. The first person will draw cards from the numbers pile. Each

person in the group is in charge of finding the mean, median, and mode of the collection of numbers.

5. The same person will then draw from the M-M-M pile. This will determine the number of points Person 1 will get.

6. Repeat Steps 4 and 5 until everyone has gone.

Round #1 draw 3 cardsRound #2 draw 4 cardsRound #3 draw 5 cardsRound #4 draw 6 cardsRound #5 draw 7 cards

Round decimals to

nearest whole number!

After the Game…• Report your game results to a

teacher• Paperclip the number cards and the

M-M-M cards together• You may begin working on the

homework assignment if you finish before the time limit

Homework: pgs. 371-372 #19-29

Exit Slip

• Work on this individually• Needs to be done before you leave• Begin working on the homework after

you turn it in

Homework: pgs. 371-372 #19-29

Mean, Median and Mode Song