Download The t-distribution approaches the normal distribution as the number

The t-distribution approaches the normal distribution as the number of degrees of
freedom decreases.
A) True
B) False
The sampling distribution of sample proportions p' is approximately distributed as
a Student’s t-distribution.
A) True
B) False
The chi-square distribution is used for inferences about the population mean µ
when the standard deviation s is unknown.
A) True
B) False
The chi-square distribution is a skewed distribution whose mean value is n for
degrees of freedom larger than two.
A) True
B) False
Independent samples are obtained by using unrelated sets of subjects.
A) True
B) False
In dependent sampling, the two data values, one from each set, that come from the
same source are called paired data.
A) True
B) False
The z-distribution is used when two dependent means are to be compared.
A) True
B) False
The standard normal score is used for all inferences concerning population
proportions.
A) True
B) False
Each F-distribution is identified by two numbers of degrees of freedom, one for
each of the two samples involved.
A) True
B) False
The chi-square distribution is used for making inferences about the ratio of the
variances of two populations.
A) True
B) False
In a two-tailed test, with n = 20, the computed value of t is found to be t* = 1.85.
Assuming the sample is randomly selected from a normal population, then the pvalue is given by:
A) 0.005 < p-value < 0.01.
B) 0.01 < p-value < 0.02.
C) 0.025 < p-value < 0.05.
D) 0.05 < p-value < 0.10.
In comparing Student's t-distribution to the standard normal distribution, we see
that Student's t-distribution is:
A) less peaked and thinner at the tails.
B) less peaked and thicker at the tails.
C) more peaked and thinner at the tails.
D) more peaked and thicker at the tails.
Which of the following would be the hypothesis for testing the claim that the
proportion of students at a large university who smoke is significantly different
from 0.15?
A) H o: p = 1.5(=), H a: p > 1.5
B) H o: p = 1.5, H a: p != 1.5
C) H o: p > 1.5, H a: p = 1.5
D) H o: p < 1.5, H a: p > 1.5
As the binomial parameter p gets larger, then q
A) gets smaller.
B) also gets larger.
C) stays the same.
D) size depends on n.
The mean age of 25 randomly selected college seniors was found to be 23.5 years,
and the standard deviation of all college seniors was 1.3 years. The correct
symbol for the 1.3 years is which of the following?
A) µ
B) s
C) σ
D) x
In a chi-square distribution, the mean is equal to the
A) degrees of freedom.
B) median.
C) mode.
D) standard deviation.
Which of the following critical values of the chi-square distribution is the largest?
A) ? 2 (20,0.025)
B) ? 2(12,0.95)
C) ? 2(8, 0.005)
D) ? 2 (15,0.90)
Studies that involve paired subjects deal with
A) dating service samples.
B) independent samples.
C) dependent samples.
D) None of the above.
You plan to test the dependent sampling claim: “a particular weight loss program
is effective in weight reduction.” What would be the null hypothesis, if d=X after
-X before?
A) Ho: µd = 0
B) Ho: µd = 0 (=)
C) Ho: µd ? 0
D) Ho: µd = 0 (=)
If two independent samples are used in a hypothesis test concerning the difference
between population means for which the combined degrees of freedom is 20,
which of the following could not be true about the sample sizes n1 and n2?
A) n1=12 and n2=8
B) n1=12 and n2=10
C) n1=13 and n2=9
D) Cannot be determined from the given information
To test the null hypothesis that the mean waist size for males under 40 years
equals 34 inches versus the hypothesis that the mean differs from 34, the
following data were collected: 33, 33, 30,
34, 34, 40, 35, 35, 32, 38, 34, 32, 35, 32, 32, 34, 36, 30.
Calculate the t* -value of the test statistic
mean= 33.833
sd = 2.526
t* = (33.833 - 34) / (2.526/sqrt(18)) = - 0.286
State the null hypothesis, Ho,and the alternative hypothesis, Ha , that would be
used to test the claim: The standard deviation has increased from its previous
value of 15.
Ho: σ ≤ 15
Ha: σ > 15
A particular candidate claims she has the support of at least 60% of the voters in
her district. A random sample of 150 voters yields 87 who support her. The
candidate wishes to test her claim at the 0.05 level of significance.
Compute the value of test statistic.
phat = 87/150 = 0.58
z=(.58 - .6) / sqrt(.6*.4/150) = -0.5
A random sample of 51 observations was selected from a normally distributed
population. The sample mean was x = 88.6 , and the sample variance was s2 =
38.2. We wish to determine if there is sufficient reason to conclude that the
population standard deviation is not equal to 8 at the 0.05 level of significance.
Calculate the value of the test statistic.
test static= X^2 = (n-1)s^2/σ^2
= (51-1)38.2/8^2
= 29.844
Consider testing Ho: µd = 0 vs. Ha: µd = > 0 with n =20 and t* =1.95.
Place bounds on the p-value using the table of “critical values of Student’s tdistribution” available in your textbook.
0.01 < p-value < 0.05
Consider the following paired data.
A54341
B21543
Calculate Sd , Sd 2 , d(bar), and sd .
A-B : 3, 3, -2, 0, -2
Σd = 3 + 3 - 2 + 0 - 2 = 2
Σd 2 = 3^2 + 3^2 + (-2)^2 + 0 + (-2)^2 = 26
d(bar) = (3 + 3 - 2 + 0 - 2)/5 = 0.4
sd = sqrt[ Σd 2 - (Σd )^2/n ] = sqrt(26 - 2^2/5) = 5.02
A group of sheep, infested with tapeworms, are randomly divided into two groups
as follows. Each sheep is assigned a number (1 through 20) and then 10 numbers
are selected by drawing 10 slips of paper from a box having the numbers 1
through 20 written on them. The drawing divides the sheep into two groups. One
group is given a placebo and the other is given an experimental drug. After six
weeks the sheep are sacrificed and tapeworm counts are made. Do these samples
represent dependent or independent samples?
Independent samples.