PAM 210 lecture 1
Problem set #10
Posted: 21
st
of April, 2008
Due date: 28
th
of April, 2008
#1) A national survey of restaurant employees found that 80% said that work stress had a
negative impact on their personal lives.
A sample of 100 employees of a restaurant chain
finds that 72 answer “Yes” when asked, “Does work stress have a negative impact on
your personal life?”
Is this good reason to think that the proportion of all employees of
this chain who would say “Yes” differs from the national proportion
p
0
= 0.80?
Perform
this test:
H
0
:
p
= 0.80
H
a
:
p
≠
0.80
a) What is the z value?
Ans.
2
100
)
8
.
0
1
(
8
.
0
8
.
0
72
.
0

≈


=
z
(2 points)
b) What is the Pvalue of the zvalue?
Ans.
P=2*P(Z≥2)=2*(1.9772)=0.0456
(2 points)
c) Do you reject the H
0
at the 5% level?
Ans.
The pvalue=0.0456<.05, so we reject the null hypothesis.
(1 point)
#2) One possible effect of air pollution is genetic damage.
A study designed to examine
this problem exposed one group of mice to air near a steel mill and another group to air in
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 Spring '08
 ABDUS,S.
 Null hypothesis, Statistical hypothesis testing, decimal places, negative impact, national proportion p0, expected cell counts

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