Transcript Measures of Variation PowerPoint

6-3 Measures of Variation
Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes
6-3 Measures of Variation
Warm Up: Solve in your notes! NO KWL
Find the mean and median of each data
set.
1. 14,24,12,20,15,22,12
mean:17 ; median:15
2. 7,13,16,9,15,6
mean:11 ; median:11
6-3 Measures of Variation
Problem of the Day
Jeff is painting a wall that is 20 feet long and 9
feet high. How many square feet of wall is he
painting?
180 sq ft
6-3 Measures of Variation
Learn calculate, interpret, and compare
measures of variation in a data set.
6-3 Measures of Variation
Vocabulary
box-and-whisker plot
quartiles
variation
inter-quartile range (IQR)
6-3 Measures of Variation
Ms. Snow asks some of her students how many pets
they have. The responses are 9, 0, 4, 1, 1, 2, 3, 5,
and 2 pets.
Quartiles are three values, one of which is the
median, that divide a data set into fourths. Each
quartile contains one-fourth, or 25%, of the data.
6-3 Measures of Variation
The interquartile range (IQR) is the difference
between the first and third quartiles.
•It is a measure of the spread of the middle 50%
of the data.
•A small interquartile range means that the data in
the middle of the set are close in value.
•A large interquartile range means that the data in
the middle are spread out.
6-3 Measures of Variation
Additional Example 1: Making a Box-and-Whisker
Plot
The average number of hours that several
students watch television in a day is given. Use
the data to make a box-and-whisker plot: 2, 1,
5, 2, 1, 2, 3, 2, 2.
Step 1 Order the data from least to greatest.
1, 1, 2, 2, 2, 2, 2, 3, 5
Step 2 Find the least and greatest values, the
median, and the upper and lower quartiles.
1
1
2
2
2
2
2
3
5
Greatest Value
Least value
First Quartile
Median
1.5
Third Quartile
2.5
6-3 Measures of Variation
6-3 Measures of Variation
Additional Example 2: Finding the Interquartile
Range
Find the inter-quartile range for the data set 87,
71, 72, 73, 84, 92, 73.
71, 72, 73, 73, 84, 87, 82 Order the data from least to
greatest.
71,
72, 73,
73, 84,
IQR=87-72=15
87,
82
Find the median and quartiles
Find the difference between the
first quartile (72) and the third
quartile (87).
The inter-quartile range is 15.
6-3 Measures of Variation
Check It Out: Example 2
Find the inter-quartile range for the data set 17,
39, 38, 9, 29, 40, 27
9, 17, 27, 29, 38, 39, 40 Order the data from least to
greatest.
9,
17, 27,
29, 38,
IQR=39-17=22
39,
40
Find the median and quartiles
Find the difference between the
first quartile (17) and the third
quartile (39).
The inter-quartile range is
22.
6-3 Measures of Variation
Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems
6-3 Measures of Variation
Lesson Quiz
A park ranger measures the thickness of ice on a
lake in 8 different locations: 19 in., 17 in., 15 in.,
15 in., 18 in., 12 in., 16 in., 14 in.
2. Find the interquartile range of the data.
3 in.
6-3 Measures of Variation
Lesson Quiz for Student Response Systems
The number of text messages 7 people sent in
one day are as follows: 8, 4, 3, 17, 2, 1, and 10.
1. Find the inter-quartile range of the data.
A. 2.5
B. 3
C. 8
D. 9.5
2.Find the mean absolute deviation of the data, to the
nearest tenth.
A. 3
B. 4.5
C. 6.4
D. 17