9.30.
Textbook answer key solution: Twotailed test.
Given:
μ
0
= 600,000 (= 600K)
n
= 40
xbar = 612,000 (= 612 K)
s
= 65,000 (= 65K)
Use:
α
= 0.10
a.
Daily viewership is 600,000 (600 K) as claimed or it isn’t (it could be
either higher or lower and which is irrelevant).
So this is a righttailed
test.
The pair of mutually exclusive hypotheses is:
H
0
:
μ
= 600
H
a
:
≠
600
This is a twotailed test.
b
. Given for the sample of
n
= 40: xbar = 612 K with
s
= 65 K
168
.
1
40
65
600
612
0
=
=
μ
=


n
s
x
t
Degrees of freedom
df
=
n
– 1 = 39
Using
t
table: Search the row
df
= 39 for a value of 1.168 or close.
Reading across the row, the value 1.168 is between 0.851 and 1.304.
Reading up the column from .0851 to the header, the area = 0.20.
Reading up from 1.304 to the header, the area = 0.10.
The
p
value is two times the upper tail area.
Using
t
table: area in upper tail is between 0.10 and 0.20.
Therefore, the
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 Spring '08
 SINGER
 Statistics, Statistical hypothesis testing, Harvey A. Singer

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