1. Introduction to Statistics
Chapter 9
Introduction to Statistics
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2. Frequency Distributions
Section 9.1 and 9.2
Frequency Distributions
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3. Copyright ©2015 Pearson Education, Inc. All right reserved.
Example:
Characterize the shapes of the given distributions for adult males. (Data from:
(a) Height (inches)
Solution:
The shape is normal because the shape peaks in the middle and tapers equally on each side.
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Example:
Characterize the shapes of the given distributions for adult males. (Data from:
(b) Body Mass Index (kg/m2)
Solution:
The shape is right skewed because the tail is to the right.
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Example:
A sample of 10 working adults was asked “How many hours did you work last week?” Their responses appear below. (Data from:
40, 35, 43, 40, 30, 40, 45, 40, 55, 20
Find the mean, median, and mode of the data.
Solution:
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Section 9.3
Measures of Variation
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Example:
Find the standard deviation for the following sample of lengths (in minutes) of eight consecutive cell phone conversations by one person:
2, 8, 3, 2, 6, 11, 31, 9.
Work by hand, using the shortcut variance formula.
Solution:
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12. Copyright ©2015 Pearson Education, Inc. All right reserved.
Example:
Find the standard deviation for the following sample of lengths (in minutes) of eight consecutive cell phone conversations by one person:
2, 8, 3, 2, 6, 11, 31, 9.
Work by hand, using the shortcut variance formula.
Solution:
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14. Normal Distributions and Boxplots
Section 9.3
Normal Distributions and Boxplots
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Example:
If a normal distribution has mean 60 and standard deviation 5, find the given z-scores.
(a) The z-score for
Solution:
(b) The z-score for
Solution:
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19. Normal Approximation to the Binomial Distribution
Section 9.5
Normal Approximation to the Binomial Distribution
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Example:
Consider a sample of 100 vehicles selected at random, where 44% of the registered vehicles are vans, pickups, or SUVs. Use the normal distribution to approximate the probability that at least 61 vehicles are vans, pickups, or SUVs.
Solution:
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22. Copyright ©2015 Pearson Education, Inc. All right reserved.
Example:
Consider a sample of 100 vehicles selected at random, where 44% of the registered vehicles are vans, pickups, or SUVs. Use the normal distribution to approximate the probability that at least 61 vehicles are vans, pickups, or SUVs.
Solution:
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