1
Chapter 13
13.38 a.
Randomly select finance and marketing MBA graduates and determine their starting
salaries.
b.
Randomly assign some MBA students to major in finance and others to major in marketing.
Compare starting salaries after they graduate.
c.
Better students may be attracted to finance and better students draw higher starting salaries.
13.58 a.
1
/
:
H
2
2
2
1
0
=
σ
σ
1
/
:
H
2
2
2
1
1
≠
σ
σ
Rejection region:
88
.
1
F
F
F
29
,
29
,
05
.
,
,
2
/
2
1
≈
=
>
ν
ν
α
or
53
.
88
.
1
/
1
F
/
1
F
/
1
F
F
29
,
29
,
05
.
,
,
2
/
,
,
2
/
1
1
2
2
1
=
≈
=
=
<
ν
ν
α
ν
ν
α
−
F =
2
2
2
1
s
/
s
= 350/700 =.50, p-value = .0669. There is enough evidence to conclude that the
population variances differ.
b.
Rejection region:
98
.
2
F
F
F
14
,
14
,
025
.
,
,
2
/
2
1
=
=
>
ν
ν
α
or
34
.
98
.
2
/
1
F
/
1
F
/
1
F
F
14
,
14
,
025
.
,
,
2
/
,
,
2
/
1
1
2
2
1
=
=
=
=
<
ν
ν
α
ν
ν
α
−
F =
2
2
2
1
s
/
s
= 350/700 =.50, p-value = .2071. There is not enough evidence to conclude that the
population variances differ.
c.
The value of the test statistic is unchanged and in this exercise the conclusion changed as
well.
.
13.67
)
p
p
(
:
H
2
1
0
−
= 0
≠
−
)
p
p
(
:
H
2
1
1
0
a.
+
−
−
=
2
1
2
1
n
1
n
1
)
p
ˆ
1
(
p
ˆ
)
p
ˆ
p
ˆ
(
z
=
+
−
−
100
1
100
1
)
425
.
1
(
425
.
)
40
.
45
(.
= .72, p-value = 2P(Z > .72) = 2(1 – .7642)
= .4716.