CHAPTER 1/8
In order to estimate the proportion of students on a campus who wake up regularly at night, a random sample of 10 students is selected from each of the freshman, sophomore, junior, and senior classes. This is an example of ...
Stratified Random Sample
What would be an appropriate display for a data set containing cause of death (heart disease, cancer, stroke, other) for a sample of 200 adults?
Pie Chart or Bar Chart
True or False: If two data sets have the same mean and median then they must be identical.
False!
True or False: A correlation of zero always means there is no relationship between x and y.
False!
True or False: Any negative z-score would be considered unusual.
False
An experiment is conducted to test the effects of a new drug on high blood pressure. 320 adults with high blood pressure participate in the experiment. The subjects are first divided into four groups according to age (20-29, 30-39, 40-49, 50-59). Within each group subjects are randomly assigned to either take the new drug or a placebo. What type of experimental design is being used for this experiment?
Randomized Block
Suppose a data set has a strong skew to the right. Which will be larger, the mean or the median?
The mean will be larger than the median.
In a study of unemployment rates for a sample of major cities, the distribution was found to be left skewed with two low outliers. What would be the appropriate measure of center for this distribution?
The median because the data is skewed.
The National Opinion Research Center at the University of Chicago conducted a survey where they obtained data involving the number of hours of watching TV in a typical day and age of the survey participants. The resulting regression equation is ...
TV Hours = 2.19 + 0.0173 (Age)
Suppose for a particular age the residual is calculated to be -3. Did this model over predict or under predict the number of hours the participant watch TV?
The model over predicts the number of hours watching television.
A data set consists of 20 values. Among these 20 values there is one outlier. If the outlier is removed form the data set, which of the following measurements must change?
Mean
Median
IQR
Only the mean will change. The median and IQR are not influenced by outliers.
In a random sample of 50 college students it was determined that the average number of hours spent studying per day was 2.15. The value 2.15 is a ...
Statistic
A fabric manufacturer conducted a study to determine the optimal method for dying fabric. Each fabric sample was assigned to one of three dyeing times (20 minutes, 30 minutes, or 40 minutes), one of two temperatures (150 or 175 degrees Celsius), and one of two roller types (metal or natural bristle). How many treatments are there in this experiment?
12
In a study of credit card charges, the distribution was found to be right skewed with several high outliers. What would be the appropriate measure of spread for this distribution?
The IQR because the data is skewed.
A study was conducted to investigate the relationship between quarterly sales (in billions of dollars) and unemployment rate (%) at a large retail store. The following regression equation was obtained:
Sales = 20.91 - 2.994 (Rate)
R-squared = 88.3 %
What is the value of the correlation coefficient describing the strength of the relationship between sales and unemployment rate?
-0.9397
An experiment is being performed to test the effects of alcohol on reaction time. Subjects were selected at random and given three beers to consume. Their reaction time to a simple stimulus was measured before and after drinking the alcohol. What type of experimental design is being used for this experiment.
Matched Pair
Undercoverage
What type of graphical display would be appropriate for displaying the weights of the players on a baseball team?
Pie Chart
Stemplot
Bar Chart
All of the above
Stemplot!
Anna scored 70 on a statistics test for which the mean was 60 and the standard deviation was 9. She also scored 59 on a chemistry test for which the mean was 50 and the standard deviation was 6. If the scores for both tests were normally distributed, on which test did she do better relative to her classmates?
Chemistry, because the z-score is farther above zero.
Data obtained for a group of college freshman examining their SAT scores (math plus verbal) from their senior year of high school and their GPA during their first year of college. The resulting regression equation to predict GPA is ...
GPA = 1.35 + 0.00161 (SAT Score)
r = 0.632
What percent of the variation in GPAs can be explained by looking at SAT scores?
39.94%
A high school athlete, David, had a z-score (standardized score) of 1.6 for his time in a race compared to the entire group of runners in the race. How should we interpret David's z-score?
David's time is 1.6 standard deviations above the average time of all the runners.
Two studies are run to compare the experiences of families living in high-rise public housing to those of families living in subsidized townhouse rentals. The first study interviews 25 families who have been in each program for at least one year, while the second randomly assigns 25 families to each program and interviews them after one year. Which study is an experiment and which study is an observational study?
The first study is an observational study, while the second is an experiment.
A researcher specialist for a large seafood company is interested in how packaging product and temperature affect bacterial growth on oysters. She plans to investigate bacterial growth on oysters subjected to three different storage temperatures (0, 5, 10 degrees) and two different packaging products (plastic, foil). At the end of two weeks, the amount of bacterial growth is measured, and the average bacterial growth for each treatment group is calculated. The experimental units and number of treatments are ...
Oysters, 6
The five number summary for the size (acres) of a sample of farms is ...
Min: 6.0
Q1: 19
Med: 35.5
Q3: 62
Max: 129
Is the largest farm an outlier?
Yes, it is more than 1.5 (IQR) above the third quartile
A study was conducted to investigate the relationship between quarterly sales (in billions of dollars) and unemployment rate (%) at a large retail store. The following regression equation was obtained:
Sales = 20.91 - 2.994 (Rate)
R-squared = 88.3 %
In one recent quarter the unemployment rate was 6% and the sales were $2.5 billion. Calculate the residual.
-0.446
A homebuilder's association lobbying for various home subsidy programs argued that, during periods of high interest rates, the number of building permits issued decreased drastically, which in turn reduced the availability of new housing. Data relating housing loan interest rates and the number of building approvals (thousands), were collected. The following regression equation was obtained:
Building Approvals (1000s) = 239.5 - 8.06 (Interest Rate)
A correct interpretation of the slope is ... ?
For each 1 percent increase in interest rate, the number of building approvals (1000s) decreases by 8.06%.