Transcript Review for Test Ch. 26

1. Which of the following is NOT true of the 2
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) 2 is defined only for positive values of the variable.
d) The area under a 2 curve is 1.
e) All of these are true about the 2 probability density
function.
2) A regression of the amount of calories in a serving of breakfast cereal
vs. the amount of fat gave the following results:
Calories = 97.1053 + 9.6525 Fat.
Which of the following is a FALSE statement?
a. It is estimated that for every additional gram of fat in the cereal, the
number of calories increases by about 9.
b. It is estimated that in cereals with no fat, the total amount of calories is
about 97.
c. If a cereal has 2 g of fat, then it is estimated that the total number of
calories is about 115.
d. If a cereal has about 145 calories, then this equation indicates that it
has about 5 grams of fat.
e. One cereal has 140 calories and 5 g of fat. Its residual is about 5 cal.
The two-way table specifies favorite ice cream flavors by gender.
Chocolate
Vanilla
Strawberry
Male
32
14
3
Female
16
4
10
3. A 2 test of significance yields a test statistic of 2 = 10.71 and a
p-value of .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 2 test should not have been preformed
due to assumption violations.
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.
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 2 statistic would be:
a) 1.79
b) 2.05
d) 4.94
e) 7.08
c) 2.92
5. The spinner in a board game has eight colors the arrow can land on. To
test the fairness results you spin the arrow 75 times:
Green: 3
Brown: 16
Blue: 13
Yellow: 14
Red: 9
White: 8
Orange: 9
Black: 3
Calculate the chi-square statistic for these data and use a table to find the pvalue.
A. ² = 14.07 , p = .05
B. ² = 17.267 , p = .984
C. ² = 17.267 , .02 > p > .01
D. ² = 9.04 , p = .25
E. ² = 9.04 , p < .05
6) The corn rootworm is a pest that can cause significant damage to corn,
resulting in a reduction in yield and thus in farm income. A farmer will examine a
random sample of plants from a field in order to decide whether or not the number
of corn rootworms in the whole field is at a dangerous level. If the farmer
concludes that it is, the field will be treated. The farmer is testing the null
hypothesis that the number of corn rootworms is not at a dangerous level against
the alternative hypothesis that the number is at a dangerous level. Suppose that
the number of corn rootworms in the whole field actually is at a dangerous level.
Which of the following is equal to the power of the test?
(A) The probability that the farmer will decide to treat the field.
On the test I will also ask about Type 1 and
(B) The probability that the farmer
decide not to treat the field.
Type 2will
errors!!
(C) The probability that the farmer will fail to reject the null hypothesis.
(D) The probability that the farmer will reject the alternative hypothesis.
(E) The probability that the farmer will not get a statistically significant result.
The following table displays by gender the number of people in a
club who favor a particular political party.
Democratic
Republican
Independent
Female
20
35
45
Male
30
25
50
7. If we were to do a chi-square test, which expression would
calculate correctly the expected frequency of the number of
females who favor the Republican Party?
60  100
205
b) 35  60
105
d) 35  205
100
e) 35  100
205
a)
c)
60  100
105
The following table displays by gender the number of people in a
club who favor a particular political party.
Democratic
Republican
Independent
Female
20
35
45
Male
30
25
50
8. What is the probability that a person chosen at random will be
female given the person favors the Democratic Party?
a) 0.4
b) 0.2
d) 0.2439
e) 0.4878
c) 0.0976
9. Your friend says she has an unfair die: the probability of getting a one or
a six is 1/3 for each, and the probability of getting a two, three, four, or five
is 1/12 for each. You want to test her statement.
What is the minimum number of times you have to roll the die to use a chisquare goodness-of-fit test here?
a) 5
b) 18
c) 39
d) 60
e) 65
10. A test of independence for data organized in a two-way table relating
number of siblings and number of family relocations is conducted using
the chi-square distribution. The p-value of the test is .045. If alpha is .05,
then which of the following is a valid conclusion of the test?
a) The mean is significant.
b) We reject the hypothesis that the variables are dependent.
c) We accept the hypothesis that the variables are
independent.
d) We have sufficient evidence to reject the hypothesis that the
variables are independent.
e) The variables are independent.
11) The table to the right provides data on
sex, political party affiliation, and income
bracket for a sample of people questioned
during a poll.
Group the bivariate data for the two
variables "sex" and "income
bracket" into a contingency table.
Answer choices are on next
slide
Sex Political Party Income Bracket
M
Rep
High
F
Dem
Middle
F
Dem
Middle
M
Dem
Low
F
Other
Middle
M
Rep
Low
F
Rep
High
M
Rep
High
M
Dem
High
F
Rep
Low
M
Dem
High
F
Rep
Middle
F
Dem
Middle
M
Dem
Middle
M
Rep
Low
F
Dem
High
M
Rep
Low
F
Other
High
M
Other
Middle
F
Dem
Low
M
Dem
Middle
M
Rep
Low
F
Dem
Middle
MC 3rd Nine weeks test
1)E
2) E
3) D
4) B
5) C
6) A
7) A
8) A
9) D
10) D
11) D