Chose the Best Measure of Central Tendancy

Find the mean, mode, median and range

Mode = 7

Median = 9
Mean = 13

Range = 43

The median is the best measure of central tendancy.

The median is the best because most of the numbers are close to 9

How many shirts should I buy for the next 30 weeks?

9 x 30 = 270

130 x 3 = 390

Find the mean, median, mode, range, and outliers

a. 12 , 20 , 18 , 15 , 10 , 10 , 12
b. 48 ,32 ,67 ,61 ,47 ,95 ,89 ,888 ,1

First (order)
a. 10 ,12 ,12 ,15 ,18 ,20
b. 1 ,32 ,47 ,48 ,61 ,67 ,89 ,95 ,888


a. mean: 14.5 b. mean: 147.56
median: 13.5 median: 61
mode: 12 mode: no mode
range: 10 range: 887
outlier: no outlier outlier: 888, 1



Effect of outliers

Some outliers need to be removed from a data set. This is typically a judgement call.

Outliers have an effect on all measures of central tendency.


http://www.schooltube.com/video/85e9382853d3425594fd/Mean-Median-Mode-Range-Outliers




Homework- Page 444-445 numbers 1-8
www.mytextbook.ca

Effects of Outliers

Some outliers need be removed from a data set. This is typically a judgement call.

Outliers have an effect on all measures of central tendency.



*Page 444 - 445, # 1 - 8 is HOMEWORK!
http://ebook.mytextbook.ca/

*Remember to have all of the number of the day pages complete by Tuesday. Mr. Isfeld will be collecting them.

Range and Outliers

Range -

The positive difference between the largest and smallest values in a data set

Eg. 6, 2, 9, 4, 3 - data set

2, 3, 4, 6, 9 - ordered from least to greatest

9 - 2 = 7

The range is 7

Eg. -8, -1, -3, -5

-8, -5, -3, -1

(-1) - (18) = 7

The range is 7

Outliers -

A value that is much smaller or larger than the other data values

A data set man have one or more outliers or no outliers

* In other words, it's just like finding something that doesn't belong

*In this case, you are looking for numbers that have a big difference between the other numbers


Find the range-

a) 7, 4, 3, 6, 2, 5, 8, 3

2, 3, 3, 4, 5, 6, 7, 8

8 - 2 = 6

The range is 6


b) 11, 8, 8, 5, 7, 6, 7, 6, 6

5, 6, 6, 6, 7, 7, 8, 8, 11

11 - 5 = 6

The range is 6


c) -4, 3, -1 , 0, 2

-4, -1, 0, 2, 3

3 - (-4) = 7

The range is 7


Find the outliers-

a) 18, 19, 79, 17, 20, 12 - 12, 17, 18, 19, 20, 79 - The range is 79

b) 14, 14, 16, 15, 1, 16 - 1, 14, 14, 15, 16, 16 - The range is 1

c) 98, 202, 99, 91, 2, 95, 89, 88, 94 - 2, 88, 89, 91, 94, 95, 98, 99, 202 - The range is 2 and 202

Page 437 - 439, # 1- 16 .... IS HOMEWORK!

http://www.mytextbook.ca/

*Reminder.. there is a math quiz tomorrow on Number of The Day, all 25 questions!

Measure of Central Tendency

Measure of central tendency
-is a value that represents the center of a set of data
-can be median, mode, mean

Remember:

-When given a set of data always reorder the digits from least to greatest.

Median
-the middle number in a set of data after the data has been arranged or ordered, only if there is an odd number of items in the data

-if there is an even number of items in the data the sum of the 2 middle numbers in the data set are divided to get the total

eg. 2, 5, 6, 8, 9, -median is 6

1, 3, 6, 8, 9, 10 -median is 7
-----(6+8) ÷ 2 =7

3, 8, 2, 6, 5, 4, -median is 4.5
2, 3, 4, 5, 6, 8,
----(4+5) ÷ 2 = 4.5

Mode
-the most frequent occurring number in the set of data

-if you find no number that repeats most often, then there is no mode.

eg. 3, 5, 7, 7, 9 -mode is 7

2, 2, 4, 6, 6, 8, 11 -mode is 2 and 6


1, 2, 3, 4 -mode; there is no mode


Try this:

Montreal scored the following goals in their last 10 games

5, 4, 3, 2, 1, 5, 3, 3, 7, 3

-Find the median and the mode:

1, 2, 3, 3, 3, 3, 4, 5, 5, 7

----------(3+3) ÷ 2 = 3

median- 3
mode- 3

Frequency Table

8, 8, 8, 10, 10, 11, 11, 11, 14, 14

----------(10+11) ÷ 2 = 10.5

median- 10.5

mode- 8, 11

Mean
-a measure of rental tendency

-the sum (adding) of a set of data divided by the number of values in set


eg. 4, 5, 8, 9, 9

- 4+5+8+9+9=35
- 35 ÷ 5 =7


Try this- mean, median, mode


a) 4, 5, 6, 7, 7, 8, 8, 9, 9

mean-7, median-7, mode-7


b) 250, 250 300, 300, 400

mean-300, median-300, mode-250, 300

Homework and extra practice

Your homework for the weekend is pages 426 - 427 numbers 1 - 17 plus the math link.

Try some of these problems for extra practice: Working With Data 1. List all the four-digit numbers that are even, have a 6 in the tens place, and whose digits add to 12. 2. Is 349 ´ 0.9 greater than, less than, or equal to 349? How do you know? ______________________________________________________________ ______________________________________________________________ 3. Suppose you know that 48 ÷ 16 = 3. Without finding the exact answer, tell whether the answer to 48 ÷ 15.99 is greater than, less than, or equal to 3. Why? ______________________________________________________________ ______________________________________________________________ 4. Use the multiplication below to answer the questions that follow. a) Can E be 2? Explain. ___________________________________________________________ ___________________________________________________________ b) What is the value of D? Why? ___________________________________________________________ ___________________________________________________________ c) What is the value of G? How do you know? ___________________________________________________________ ___________________________________________________________

Review: Solving One Step Algebra Equations

Apply the opposite operation

Remember
-an opposite operation is an operation that "undoes" another operation.
-subtraction and adding are opposites
-division and multiplication are opposites
-whatever you do one side you must do the same to the other side to maintain balance


1st step- isolate the variable/get the letter by itself
2nd step- apply opposite operation
3rd step- check the answer, substitute the answer for the letter of the original equation

A+5=7
-5 -5
A=2
Check your answer:
A+5=7
2+5=7
7=7

To extend our knowledge, we had equations to solve:

a) b-3=5
- +3 +3
- b=8
Check your answer:
b-3=5
8-3=5
8=8

b) c÷3=7
- x3 x3
- c=21
Check your answer:
c÷3=7
21÷3=7
21=21

c) 4d=16
- ÷4 ÷4
- d=4
Check your answer:
4d=16
4(4)=16
16=16

Other examples:



















HOMEWORK: Pg. 405=407 #1-21

Solving One Step Equations

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