Download 1)The variable of interest in a study is the political party affiliation

1)The variable of interest in a study is the political party affiliation (Democrat, Republican, or
Independent) in a sample of 100 voters. What is the nature of this variable of interest?
A) Quantitative
B) Qualitative
C) None of the above
2. Statistical inference is complete without a measure of its reliability.
A) True
B) False
3. Calculate the standard deviation of the data set: 8, -2, 1, 3, 5, 4, 4, 1
A) 9
B) 3.02
C) 2.18
D) 2.82
4. What is the 50th percentile of a quantitative data set called?
A) Median
B) Mode
C) Mean
D) Average
5. For mound-shaped and symmetric frequency distributions of data sets, approximately what percentage
of measurements has a z-score between -2 and 2?
A) 68%
B) 4%
C) 99.7%
D) 95%
6. If the data set is skewed to the left, then the __________ is less than the
A) mean; median
B) median; mean
C) mean; relative frequency
D) relative frequency; mean
7. Two fair dice are tossed, and the up face on each die is recorded. Find the probability that both dice
show the same number.
A) 16.7%
B) 50%
C) 6%
D) 1.6%
8. How many different samples can be drawn if you wish to sample n = 2 elements from a total of N =
10 elements?
A) 45
B) 20
C) 8
D) 5
9. Events A and B are _______________ if A ∩ B contains no sample points – that is, if A and B have no
sample points in common.
A) Independent
B) mutually exclusive
C) undefined
D) dependent
10. Classify the random variable ‘barometric pressure at a location’ as discrete or continuous.
A) Discrete
B) Continuous
11. Which of the following two distributions is not a valid probability distribution for a discrete random
variable x?
A
X
P(x)
B
x
P(x)
0
0.2
1
0.3
2
0.3
3
0.3
2
0.15
3
0.2
4
0.4
5
0.25
12. Find the value of z0 of the standard normal random variable z such that P(z ≥ z0) = .0057
A) 0.4943
B) 0.01
C) 2.53
D) 0
13. Suppose x is a normally distributed random variable with µ=11 and s=2. Find each of the following.
P(x=7.62)
A) -0.0455
B) 0.4545
C) 0.4988
D) 0.9545
14. The following table summarizes the changes in both the SAT-Mathematics and SAT-Verbal scores for
students who paid a private tutor to help them improve their SAT scores. Assume that both distributions
of SAT score changes are approximately normal:
Mean change in score
Standard deviation of changes in score
SAT-Math
19
65
SAT-Verbal
7
49
Find the probability that a student increases his or her score on the SAT-Verbal test by at least 50 points.
A) 0.1894
B) 0.3106
C) 0.8775
D) 0.3156
15. The standard normal distribution has a mean ________ and standard deviation _______
A) 0,1
B) 1,0
C) 1,1
D) μ,σ2
16. Suppose a random sample of n = 25 measurements is selected from a population with the mean µ =
100 and standard deviation σ = 25. Give the value of σx
A) 100
B) 5
C) 4
D) 1
17. The population parameter for standard deviation is
A) p
B) p
C) σ2
D) σ
18. A random sample of 90 observations produced a mean x = 25.9 and a standard deviation of s = 2.7.
Find a 95% confidence interval for the population mean µ.
A) (25.34, 26.46)
B) (25.17, 16.63)
C) (25.841, 25.958)
D) (25.53, 26.17)
19. What happens to the width of a confidence interval as the value of the confidence coefficient is
increased while the sample size is held fixed?
A) Increases
B) Decreases
C) Remains unchanged
20. Binomial and Poisson distributions are types of _______ probability distribution
A) Discrete
B) Continuous
C) Frequency
D) Hypergeometric