Transcript Lesson 5-8 Pages 238-242 Measures of Central Tendency

Lesson 5-8 Pages 238-242
Measures of
Central
Tendency
Lesson Check 5-7
What you will learn!
1. How to find the mean,
median, and mode as
measures of central tendency.
2. How to use the mean,
median, and mode.
Measures of central tendency
Mean
Median
Mode
What you really need to know!
When working with numerical
data, it is often helpful to use
one or more numbers to
represent the whole set.
These numbers are called
measures of central tendency.
What you really need to know!
Statistic
Definition
sum of the data divided
Mean by the number of items
in the set
middle number of the
Median
ordered set
number or numbers that
Mode
occur most often
Example 1:
The revenue of the Top 10 Movie
10 highest
Revenues
grossing movies as (millions of $)
of June 2000 are
601
330
given in the table.
461
313
Find the mean,
431
309
median, and mode 400 306
of the revenues.
357
290
Example 1:
Mean
601
330
461
313
431
309
400
306
357
+ 290
$379.8 million
3,798
3,798 ÷ 10
379.8
Example 1:
Median$343.5 million
290 306 309 313 330 357 400 431 461 601
330 + 357 = 687
687 ÷ 2 = 343.5
Example 1:
Mode
No Mode
290 306 309 313 330 357 400 431 461 601
This is no number or
numbers that appear
more than any other
number. Therefore
there is no mode.
Example 2:
The line plot on the next screen
shows the number of gold
medals earned by each country
that participated in the 1998
Winter Olympic Games in
Nagano, Japan. Find the Mean,
median, and mode for the gold
medals won.
Example 2:
x
x
x
x
x
x
x
x
x
x x x x
x x x x
There are 24
numbers in this
set of data!
x x
x x
x x
x
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Example 2:
0+0+0+0+0+0
+0+0+0+1+1+
2 + 2 + 2 + 2 +3 + 3
+
5
+
5
+
6
+
6
+
9
+
x
x
x
x
x
x
x
x
x
x x x x
x x x x
10 +x 12
x
x x
= 69
x x
x
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Example 2:
69 ÷ 24 =
2.875 mean
x
x
x
x
x
x
x
x
x
x x x x
x x x x
x x
x x
x x
x
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Example 2:
The numbers are all ready
in order. Since there are 24
numbers, the median would
be 12 from the top and
bottom of the line plot.
x
x
x
x
x
x
x
x
x
x x x x
x x x x
The median is 2.
x x
x x
x x
x
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Example 2:
The mode is 0
x
x
x
x
x
x
x
x
x
x x x x
x x x x
x x
x x
x x
x
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Example 3:
The quiz scores for a
math class are 8, 7, 6, 10,
8, 8, 9, 8, 7, 9, 8, 0, and
10. Identify an extreme
value and describe how it
affects the mean.
Example 3:
0 6 7 7 8 8 8 8 8 9 9 10 10
0 is an extreme value.
Mean with 0 is 7.5
Mean without 0 is 8.2
The 0 lowers the mean by
0.7 points.
Example 4:
The table shows the monthly
salaries of the employees at two
bookstores. Find the mean,
median, and mode for each set
of data. Based on the averages,
which bookstore pays its
employees better?
Median
The Reading
Bob’s Books
Place
1290
1400
1400
1450
Mode
1400
1550
1600
1600
3650
2000
9340 ÷ 5
$1868
8000 ÷ 5
$1600
Median
Bob’s
Books
Mean
Median
Mode
$1,868
$1,400
$1,400
The
Reading
Place
$1,600
$1,550
No Mode
The Reading Place pays
its employees better.
Example 5:
Jenny’s bowling average
is 146. Today she bowled
138, 140, and 145. What
does she need to score
on her fourth game to
maintain her average?
Example 5:
146 • 4 = 584
138 + 140 + 145 = 423
584 – 423 = 161
Jenny needs to score at least
161 on her fourth game.
Page 241
Guided Practice
#’s 3-9
Read:
Pages 238-240
with someone at
home and study
examples!
Homework: Pages 241-242
#’s 10-16 all
#’s 21-35
Lesson Check 5-8
Page
735
Lesson 5-8
Lesson Check 5-8