1.
1. Consider the following bar chart of Baskepoints sources.
Three of the following statements are correct, one is NOT. Which of the following statements is incorrect?
Correct Answer
D. The distribution is skewed to the left.
Explanation
Bar graph does not have a shape or distribution because you can reorder the categories and the shape changes.
2.
Consider the following 5number summary of 120 NBA teams scores:
Which of the following observations in the data set would be called a suspected outlier?
Correct Answer
D. An observation greater than 145
Explanation
Upper Outlier=Q3+1.5(Q3Q1)=100+1.5(10070)= 145
Lower Outlier=Q11.5(Q3Q1)=1001.5(10070)=25
3.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
T F Both distributions are skewed to the left.
Correct Answer
A. True
Explanation
The "lines" determine the skewness. Since the left lines are longer for Provo and SLC, then they are both leftskewed.
4.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
1. T F Fifty percent of the SLC students scored approximately between 65 and 85.
Correct Answer
A. True
Explanation
50% of the data are between Q1 to Q3.
5.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
1.
T F Scores exhibit less spread for Provo than SLC.
Correct Answer
B. False
Explanation
Spread is measured by the IQR=Q3Q1 or the length of the box. Since the length of the box for Provo and SLC are equal, therefore, they have the same spread.
6.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
The interquartile range for SLC is about 20.
Correct Answer
A. True
Explanation
IQR=Q3Q1=8565=20
7.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
The proportion of Provo scoring between 62 to 82 is greater than the proportion of SLC scoring between 65 to 85.
Correct Answer
B. False
Explanation
The percentage of the data between Q1 to Q3 is always 50%. SO they are the same.
8.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
The mean is greater than the median for scores in Provo.
Correct Answer
B. False
Explanation
SInce Provo is leftskewed, then the mean is less than than the median.
9.
Here are the boxplots of Stats221 Final scores for Provo and Salt Lake Campus:
The proportion of SLC scoring below 85 is larger than the proportion of Provo scoring below 85.
Correct Answer
B. False
Explanation
For SLC, 75% of the data falls below 85. However, for Provo, greater than 75% of the data falls below 85.
10.
Which of the following graphical displays can be drawn using only the 5 number summary?
Correct Answer
E. Boxplot
Explanation
boxplot is created from the fivenumber summary .
11.
Which one of the following is a FALSE statement about statistical problem solving?
Correct Answer
E. Giving measure of confidence is not necessary when reporting results of statistical inference.
Explanation
Giving measure of confidence is necessary when reporting results of statistical inference.
12.
What does the standard deviation of a distribution measure?
Correct Answer
B. Spread
Explanation
Standard deviation measures spread.
13.
Coach Sloan is testing a new method of shooting free throws and plans to randomly assign 20 players to the new method 25 players to the traditional method. The mean percentage of free throws will then be compared between these two groups. What type of study is this?
Correct Answer
D. A completely randomized experiment.
Explanation
It is a completely randomized experiment.when the subjects are randomly assigned to the treatments.
It is a randomized block when the subjects are separated first by "gender" then each gender is assigned to the treatments.
14.
A financial adviser told you that it is better to invest your money in the stock market than putting it in the bank. Assume that the distribution of stock returns is normal with mean µ=10.05% and standard deviation, σ=12.12% per year. Find the proportion of people who invested in the stock market that get less than 8% return on a typical year.
Correct Answer
C. 0.4325
Explanation
z=(810.05)/12= .17
From the Normal Table, the probability to the left of the zscore is 0.4325
15.
A researcher wants to know the average dating expenses for BYU single students. The researcher obtained a list of single students from the Records Office who live in the BYU dorms. From this list , 50 students are randomly selected. The 50 students are contacted by phone and the amount they spent on dates are recorded. The average dating expense of the 50 students is $35 with a standard deviation of $8. A critic of the research project argued that the results lack believability because some single students do not live in BYU dorms. This critic is arguing that the study suffers from
Correct Answer
C. Undercoverage.
Explanation
Undercoverage occurs when some members of the population cannot be selected as part of the sample.
Nonresponse is when the survey is not returned.
16.

Which of the following constitutes a multistage sample 28 elementary school students in the Provo school district?
Correct Answer
C. Randomly select 4 elementary schools in the Provo district; from each of the selected schools randomly select one grade class; from each of the selected classes randomly select 7 students.
Explanation
Multistaged is randomly select from groups, then do SRS to each group selected.
Stratified is to do SRS for every group.
17.
The mean points of NBA players is 20 points a game with a standard deviation of 5. The mean points for the PBA (Philippine Basketball Association) is 30 with a standard deviation of 10. Wesley scores 22 points a game for the NBA while Doria scores 31 points a game for the PBA. Who has scores the highest in their league?
Correct Answer
A. Wesley
Explanation
Wesley z=(2220)/5=0.4
Doria z=(3130)/10= 0.1
The higher the zscore the better the performance.
18.
When should we use a probability sample?
Correct Answer
A. So the sample can be used to make inferences about the population.
Explanation
We use probability sample (SRS, Stratified, Multistaged) so the sample can be used to make inferences about the population.
19.
A researcher wants to know whether clean air filter improves gas mileage. 10 vehicles were randomly selected. For each vehicle, a coin is tossed. If it is heads, a clean air filter is installed first in the vehicle and the average mileage is computed. After the testing, a dirty air filter is installed and the average mileage is computed. If it is tails, then a dirty air filter is installed first and then a clean air filter is installed next. This study is an example of
Correct Answer
C. A matched pairs experiment
Explanation
Matchedpairs is when each subject gets both treatments.
20.
After a Church game, Jeremiah scored 40 points. His coach, who is a Statistics teacher, told him that the standardized score (zscore) for his points on the game, is 2.5. What is the best interpretation of this standardized score?
Correct Answer
D. Jeremiahâ€™s scoring is 2.5 standard deviations above the average scoring in the league.
Explanation
zscores implies the number of standard deviations a particular data is above or below the mean.
21.
Coach Sloan is wants to know how different feet positions affect shooting field goal percentage. He randomly assigns 30 players to 3 different feet positions. He compares the field goal percentages among the three groups. This study is an example of
Correct Answer
A. A completely randomized experiment
Explanation
It is a completely randomized experiment.when the subjects are randomly assigned to the treatments.
It is a randomized block when the subjects are separated first by "gender" then each gender is assigned to the treatments.
22.
A study was conducted using growing rats to examine the effect of jumping height on the strength of bones. Thirty rats were randomly allocated into groups. The first group of rats did low jumps of 30 cm. And the second group of rats did high jumps of 60 cm. After 8 weeks of 10 jumps per day, 5 days per week, the bone density of the rats was measured in mg/cm^{3}. What is the explanatory variable?
Correct Answer
B. Height of jump
Explanation
The study is the "effect of jumping height on the strength of bones" The explanatory is the jumping heights and the response is strength of bones measures as bone density.
23.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
Which of the following is the most reasonable value for the median of the distribution?
Correct Answer
C. 53
Explanation
The median is the middle data. There are 226 data, therefore the middle data is 226/2=113th and 114th.
By reading the frequency we can see that the 113th and the 114th data are in the "5054" bar.
24.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
What is the rough estimate of the standard deviation of the above histogram?
Correct Answer
D. 7
Explanation
estimate of standard deviation=range/6=(maxmin)/6=(6222)/6=6.7 or 7
25.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
How does the mean and median compared for this distribution?
Correct Answer
A. The mean is less than the median
Explanation
Since the histogram shows a leftskewed distribution then the mean is less than the median.
26.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
What is the appropriate measure of spread for the distribution of religiosity in the above problem?
Correct Answer
D. IQR of religiosity
Explanation
IQR is the appropriate measure of spread for skewed distribution.
27.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
What is the most reasonable value for Q1, the first quartile, of the 226 religiosity values in the previous question?
Correct Answer
B. 44
Explanation
Q1 is the 1/4 of the data. 226/4=57th data.
the 57th data falls in the "4246" bar by counting the frequencies from the left.
28.
Refer to the histogram below. It is a frequency histogram of Religiosity among 226 randomly selected college students.
Why does the histogram above represent a distribution?
Correct Answer
D. Because values for Religiosity are given on the horizontal axis and the bars represent their frequencies.
Explanation
The definition of a histogram is that the xaxis represents the data and the yaxis represents the frequencies of the data.
29.
Church League scoring follows a normal distribution with 16% of the scores greater than 41.4 and 16% less than 38.8. What is the standard deviation for these scores?
Correct Answer
A. 1.3
Explanation
"16% of the scores greater than 41.4 and 16% less than 38.8." implies that 68% of the data is between 41.4 and 38.8.
From the Empirical rule (689599.7), we can conclude that 68% of the data is between 1 standard deviatio abobve the mean and one standard deviation below the mean, for a total of 2 standard deviations.
Therefore, standard deviation = (41.438.8)/2=1.3
30.

A researcher wants to know the average dating expenses for BYU single students. The researcher obtained a list of single students from the Records Office who live in the BYU dorms. From this list , 50 students are randomly selected. The 50 students are contacted by phone and the amount they spent on dates are recorded. The average dating expense of the 50 students is $35 with a standard deviation of $8. What is the population of interest?
Correct Answer
B. All BYU Single students.
Explanation
Since the study refers to "BYU SIngle Students", then the population is "ALL BYU SIngle Students".
31.
A Sunday school teacher records the attendance for the first 10 meetings. A record of the attendance is shown below.
42 46 30 43 43 8 41 40 43 44
Considering the distribution of the data, which value best summarizes the attendance at the Sunday School meetings?
Correct Answer
B. 42.5
Explanation
This data has an outlier, which is 8. Therefore, the median best summarizes this data.
8 30 40 41 42 43 43 43 44 46
Median=(42+43)/2=42.5
32.
Below is a backtoback stemplots of the number of A’s in a stats221 class for Provo an SLC for the last 33 semesters:
Which of the following is most correct?
Correct Answer
B. Provo has a higher average, but SLC has s smaller variability.
Explanation
Since Provo has more higher data, then it is more variable and higher mean.
The SLC does not have data higher than Provo, therefore, it has less spread and the mean is lower.
33.
Given the figure below:
If basketballs X, Y, and Z are added to the group of five balls at the left, how will the standard deviation of the volume of the new 8 balls compare with the standard deviation of the volume of the original set of 5? The standard deviation of the volume of the new set of 8 balls will be _________ the standard deviation of the volume of the original 5 balls. Fill in the blank.
Correct Answer
A. Smaller than
Explanation
Standard deviation decreases when adding data equal to the mean.
Standard deviation increases when adding data above or below the mean.
34.
To investigate the effects of playing basketball, 100 men in the 4050 age range who play basketball were located. Also, 100 men of the same age and weight ranges, who had never played basketball, were located. The incidence of constipation was compared between the two groups. What kind of study is this?
Correct Answer
E. An observational study
Explanation
This is only an observational study because we are not "forcing" the subjects to the treatments. We are only "observing".
35.
The NBA scores are normally distributed. Approximately what percent of these scores will fall between one standard deviation below the mean and two standard deviations above the mean?
Correct Answer
D. 82%
Explanation
1 standard deviation below the mean is 68%/2=34%.
2 standard deviations above the mean=95%/2=47.5
34% + 47.5% = 81.5% or 82%
36.
What do we mean when the difference between two treatments, in a comparative experiment, are statistically significant?
Correct Answer
D. Too large to claim that the difference is due to chance
Explanation
Definition of Statistical significance: too large to claim that the difference is due to chance
37.
A study measured the Forced Expiratory Volume (FEV, a measure of lung capacity for which higher numbers mean more lung capacity) on several school children ranging in age from 6 to 18. The study also asked the children if the are or have been smokers. Surprisingly the average FEV computed for smokers is higher than the average FEV for nonsmokers. Which of the following should we consider when interpreting results from this study:
Correct Answer
B. Age and height might be lurking variables because older kids will have larger lungs and will be more likely to smoke.
Explanation
Lurking variables affect the response variables but the data have not been verified.
38.
The Statistics Department reported that there was a total of 3,215 Stats221 classes that have been offered with a mean enrollment of 55 and a standard deviation of 15. A random sample of 200 Stats221 classes had a mean enrollment of 51 and a standard deviation of 12. What symbols are commonly used to denote these values?
Correct Answer
A. A
Explanation
mu=population mean
sigma=population standard deviation
xbar=sample mean
s = sample standard deviation
39.

In order to assess opinions of BYU single students about the stated curfew regulation, a random sample of BYU single students were selected from each Singles Ward in BYU. What type of sample is this?
Correct Answer
B. Stratified random sample
Explanation
Multistaged is randomly select from groups, then do SRS to each group selected.
Stratified is to do SRS for every group.
40.
Which is the BEST graphical method for presenting the distribution of a categorical variable?
Correct Answer
D. Bar grapH
Explanation
Bar graph is the BEST graphical method for presenting the distribution of a categorical variable.
Histogram is is the BEST graphical method for presenting the distribution of a quantitative or numerical variable.
41.
Which interval below will contains the most data?
Correct Answer
E. E
Explanation
a. 0%
b. 68%/2=34%
c. 95%/225=22.5%
d. 25%
e. 50%
42.
A Portfolio Manger is interested in studying the effects of some variables on stock returns. Which of the following variables is quantitative?
Correct Answer
D. Cash Flow
Explanation
Cash flow is the only quantitative data.
43.
Which density curve has the smallest standard deviation?
Correct Answer
C. C
Explanation
Density "C" has more data closer to the mean, therefore, it has the smallest standard deviation compared to "A" or "B".
44.
Which of the following is a benefit of a randomized block design compared to a completely randomized design?
Correct Answer
B. Blocking reduces chance variation by removing variation associated with the blocking variable.
Explanation
benefit of a randomized block design compared to a completely randomized design is Blocking reduces chance variation by removing variation associated with the blocking variable..
45.
Given a histogram, how will you approximate the standard deviation?
Correct Answer
D. Range divide by 6
Explanation
approximate standard deviation = Range divide by 6
46.
A Sunday school teacher records the attendance for the first 10 meetings. A record of the attendance is shown below. What is the Interquartile Range (IQR)?
42 46 30 43 43 8 41 40 43 44
Correct Answer
E. 3
Explanation
8 30 40 41 42  43 43 43 44 46
Min Median=(42+43)/2=42.5
Q1=40
Q3= 43
IQR=Q3Q1=4340=3
47.
A Sunday school teacher records the attendance for the first 10 meetings. A record of the attendance is shown below. Which measure of center best summarizes the attendance at the Sunday School class?
42 46 30 43 43 8 41 40 43 44
Correct Answer
B. 43
Explanation
8 30 40 41 43 43 43 44 46
The middle data is 43.
48.
When looking at the histogram below, how do the mean and median compare?
Correct Answer
D. The mean is less than the median.
Explanation
The mean is less than the median for leftskewed distribution.
49.
A financial adviser told you that it is better to invest your money in the stock market than putting it in the bank. Assume that the distribution of stock returns is normal with a mean of 10.05% and a standard deviation of 12.12% per year. You want to invest in a strategy that results in the highest 4% of the returns. Thus you will select an investment with a return higher than ________.
Correct Answer
C. 31.26
Explanation
x = mu + z*sigma
From the Normal Table, z=1.75 has 96% to the left.
x=10.10 + (1.75)(12.12)= 31.26
50.
A financial adviser told you that it is better to invest your money in the stock market than putting it in the bank. Assume that the distribution of stock returns is normal with a mean of 10.05% and a standard deviation of 12.12% per year. Find the proportion of people who invested in the stock market that get between 8 to 11% return on a typical year.
Correct Answer
A. 0.0994
Explanation
z=(810.05)/12.12= 0.17
z=(1110.05)/12.12= 0.08
From the Normal Table,
the percentage to the left of z=0.08 is 0.5319
the percentage to the left of z= .17 is 0.4325
the percentage between the zscores is =.5319  0.4325 = 0.0994