Exam 3 Review answers
1.
(8.43, 11.97) since σ is known us it rather than s
a.
We are 92% confident that the population average time that children who need braces
wear braces is between 9.74 and 10.66 months.
3.
a.
0.58
b.
(0.57, 0.59)
4.
a.
Ho:
µ <
259 Ha: µ > 259
b.
Ho: p = 0.35 Ha: p ≠ 0.35
5.
a
6.
Ho: µ >
300
Ha:
µ < 300
pvalue = 0.99
Don’t reject Ho.
The average cost of textbooks per quarter is at least $300.
Type I error:
I believe the cost of textbooks per quarter is less than $300, when, in fact, it
is at least $300.
Type II error: I believe the cost of textbooks per quarter is at least $300, when, in fact it is
less than $300.
7.
Ho:
p >
0.47
Ha:
p < 0.47
pvalue = 0.1099
Don’t reject Ho.
The approval rating is at lest 47%.
Type I error: To believe that the percent is less than 47%, when, in fact, it is at least 47%.
Type II error: To believe that the percent is at least 47%, when, in fact, it is less than
47%.
8.
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 Fall '11
 Plum
 Statistics, United States dollar, Type I and type II errors, type ii error, A. Ho

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