Chapter 13 Test Review 2
1. Which of the following is not true of the X2 probability density function?
(a)
For small degrees of freedom, the curve displays right-skewness.
(b)
As the degrees of freedom increase, the curve approaches a normal curve.
(c)
X2 is defined only for positive values of the variable.
(d)
The area under a X2 curve is 1.
(e)
All of these are true about the X2 probability density function.
For questions 2 and 3, use the two-way table specifying favorite ice cream flavors by gender.
Male
Female
Chocolate
32
16
Vanilla
14
4
Strawberry
3
10
2. What is the expected number of males who prefer chocolate?
(a)
27.8
(b)
29.2
(c)
31.3
(d)
36.3
(e)
None of these.
3. A X2 test of significance yields a test statistic of X2 = 10.71 and a P-value of 0.005 with df = 2.
Which of the following is a valid conclusion from this information?
(a)
We have sufficient evidence of an association between gender and ice cream flavor
preference at the 5% level.
(b)
There is insufficient evidence of a relationship between gender and ice cream flavor
preference.
(c)
Since we are dealing with the two genders, a two-sample t-test is more appropriate.
(d)
No conclusion since a X2 test should not have been performed.
(e)
The information given is not sufficient to draw a conclusion.
4. A genetic model for offspring of two Labrador retrievers states:
black:yellow:chocolate = 5:4:1 (these are the ratios for dog colors)
Two Labrador retrievers are bred and a litter consisting of 3 black dogs, 5 yellow dogs, and 2
chocolate dogs is produced. For a goodness of fit test, the X2 statistic would be:
(a)
1.79
(b)
2.05
(c)
2.92
(d)
4.94
(e)
7.08
5. Each person in a 1989 random sample of prison inmates was classified according to the type of
offense committed, resulting in the following one-way frequency table. In 1983, it was
reported that 30.7% of inmates had been convicted of violent crimes, 38.6% of crimes against
property, 9.3% of drug-related crimes, 20.6% of public-order offenses, and 0.8% of other
types of crimes. Does this data provide sufficient evidence to conclude that the true 1989
proportions falling in the various offense categories are not all the same as in 1983? Test the
relevant hypotheses using α = 0.05.
Frequency
Violent crime
Crimes
Against
Property
Drug-related
Crimes
Public-order
offense
Other
225
300
230
228
16
6. Do women have different patterns of work behavior than men? The article “Workaholism in
Organizations: Gender Differences” attempts to answer this question. Each person in a
random sample of 423 graduates of a business school in Canada were polled and classified by
gender and workaholism type, resulting in the accompanying table:
Female
Male
Work Enthusiasts
20
41
Workaholics
32
37
Enthusiastic
Workaholics
34
46
Unengaged Workers
43
52
Relaxed Workers
24
27
Disenchanted
Workers
37
30
Test the hypothesis that gender and workholism type are independent, assuming that the
random sample of graduates are representative of ALL workers.
7. 352 high school students read a story describing a date rape. To investigate the effect of the
victim’s clothing on subject’s judgment of the situation described, either a photograph of the
victim dressed provocatively, a photo of the victim dressed conservatively, or no picture
accompanied the story. Each student was asked whether the situation described in the story
was one of rape. The resulting data is given in the accompanying table. Is there evidence that
the proportion who believe that the story described a rape differs for the three different
photo groups?
Provocative
Conservative
No Picture
Rape
80
104
92
Not rape
47
12
17
Toÿt
Ho'
1ÿ:
11 b