One-Variable Data Analysis
What measure of center is most resistant to extreme values?
(A) Mode
(B) Interquartile range
(C) Mean
(D) Median
(E) Range
(C) Mean
Which of the following statements is true about block design?
I. Treatments are assigned haphazardly to experimental units.
II. It controls for the effects of confounding variables.
III. Experimental units are examined before receiving treatments.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only
(D) II only
The average height of women between the ages 30–39 is 163.2 centimeters with a standard deviation of 9.3 centimeters. Find the probability that a woman in this age group is over 160 centimeters if it is known that the distribution is approximately normal.
(A) 0.3669
(B) 0.3655
(C) 0.6331
(D) 0.6360
(E) 0.3660
(D) 0.6360
What is the critical value z of a 99% confidence interval?
(A) 1.645
(B) 2.33
(C) 2.345
(D) 2.576
(E) 2.75
(D) 2.576
A scientist is testing whether a new fertilizer increases the height of a particular plant. As part of the experiment, 15 of the plants are randomly assigned the new fertilizer and 15 are randomly assigned an old formula. What type of test should be used to determine whether the average height of the plants is higher using the new fertilizer?
(A) A matched-pairs t-test
(B) A one-sample proportion z-test
(C) A two-sample t-test
(D) A two-sample proportion z-test
(E) A chi-squared test of association
(C) A two-sample t-test
Using this dataset, calculate the mean and the standard deviation.
{3, 8, 10, 3, 12, 7, 10}
(A) Mean is 7.5; standard deviation is 3.5
(B) Mean is 7.6; standard deviation is 3.5
(C) Mean is 7.6; standard deviation is 12.3
(D) Mean is 7.6; standard deviation is 4.0
(E) Mean is 8.0; standard deviation is 4.0
(B) Mean is 7.6; standard deviation is 3.5
The purpose of doing an experiment is to:
(A) Determine cause and effect
(B) Identify confounding variables
(C) Identify lurking variables
(D) Control participants
(E) Find human error
(A) Determine cause and effect
If SAT scores are normally distributed with a mean of 500 and a standard deviation of 100, what minimum score is needed to ensure that you are in the top 7%?
(A) 640
(B) 500
(C) 645
(D) 650
(E) 648
(E) 648
When comparing a 95% confidence interval with a confidence interval of 99% created from the same data, how will the intervals differ?
(A) The sample must be known to determine the difference.
(B) The mean of the sample must be known to determine the difference.
(C) The 95% interval will be wider than the 99% interval.
(D) The 95% interval will be narrower than the 99% interval.
(E) The use of the t-distribution or the z-distribution will determine how the two intervals differ.
(D) The 95% interval will be narrower than the 99% interval.
The mean weight of 120 male high school seniors is 156 pounds with a standard deviation of 23 pounds. Assuming the distribution of weights is approximately normal, which type of test should be used to determine whether the mean weight of all high school seniors is more than 150 pounds?
(A) A matched-pairs t-test
(B) A one-sample proportion z-test
(C) A two-sample t-test
(D) A one-sample t-test
(E) A two-sample proportion z-test
(D) A one-sample t-test
In a normally distributed dataset with a mean of 13 and a standard deviation of 2, if the data are standardized by subtracting the mean and dividing by the standard deviation, which of the statements best describes the resulting distribution?
(A) Normal with a mean of 13 and a standard deviation of 2
(B) Normal with a mean of 0 and a standard deviation of 2
(C) Normal with a mean of 0 and a standard deviation of 1
(D) Normal with a mean of 6.5 and a standard deviation of 2
(E) Normal with a mean of 6.5 and a standard deviation of 1
(C) Normal with a mean of 0 and a standard deviation of 1
The purpose of blocking in experimental design is to:
(A) Control for confounding variables
(B) Control experimenter bias
(C) Control for lurking variables
(D) Replicate the experiment
(E) Organize experimental units
(A) Control for confounding variables
In a statistics course, the probability that a randomly selected student has taken a calculus course is 0.14, while the probability that a randomly selected student drives to campus is 0.48. If the two events are independent, what is the probability that a randomly selected student in this statistics course has taken a calculus course and drives to campus?
(A) 0.07
(B) 0.14
(C) 0.34
(D) 0.48
(E) 0.62
(A) 0.07
In a test to check pH level, 49 samples showed its level to be 2.4 and with a standard deviation of 0.35. Find the 90% confidence interval estimate for the mean pH level.
(A) 2.4 ± 0.01
(B) 2.4 ± 0.08
(C) 2.4 ± 0.32
(D) 2.4 ± 0.35
(E) None of the above
(B) 2.4 ± 0.08
In 1999, 45% of freshman at a particular college had enrolled in an introductory English course. In a sample of 800 students this year, 460 freshman had enrolled in an introductory English course. Which type of test should be used to determine whether the percentage has increased since 1999?
(A) A matched-pairs t-test
(B) A one-sample proportion z-test
(C) A two-sample t-test
(D) A one-sample t-test
(E) A two-sample proportion z-test
(B) A one-sample proportion z-test
Which of the statements is true about the standard deviation?
I. It depends on the mean.
II. It is sensitive to the spread.
III. It is not resistant to extreme values.
(A) I only
(B) I and III only
(C) II and III only
(D) II only
(E) III only
(C) II and III only
What are the advantages of an experiment over an observational study?
I. Outcomes will naturally change over time.
II. The researcher has more control of the environment and treatment.
III. There is more diversity in the sample of subjects.
(A) I only
(B) I and III only
(C) I and II only
(D) II only
(E) III only
(D) II only
An experiment consists of 31 independent trials. The probability that any one trial is a failure is 45%. Which is the best estimate of the probability that more than 20 trials will be failures?
(A) 0.01
(B) 0.02
(C) 0.11
(D) 0.89
(E) 0.99
(B) 0.02
What is the critical t-value of a 95% confidence interval estimate for a sample size of 25?
(A) 2.06
(B) 1.711
(C) 2.064
(D) 1.708
(E) None of the above
(A) 2.06
A sample of 15 from a normal population yields a sample mean of 43 and a sample standard deviation of 4.7. What is the p-value that should be used to test the claim that the population mean is less than 45?
(A) 0.0608
(B) 0.1216
(C) 0.4696
(D) 0.9392
(E) The p-value cannot be determined from the given information
(A) 0.0608
Which of the statements is true about outliers?
I. They are natural variation but rare.
II. They may indicate that something may be wrong with the data collection process.
III. They should be identified.
(A) I only
(B) I and III only
(C) I, II, and III only
(D) II only
(E) III only
(C) I, II, and III only
The mathematics department wishes to form a sample from each of 10 courses offered. They randomly select three individuals from each course and include them in the 30-person sample. Which of the following methods was used to select the probability sample?
(A) Random
(B) Systematic
(C) Stratified
(D) Cluster
(E) Simple random
(C) Stratified
The probability that any one trial out of 23 independent trials will be successful is 17%. Find the probability that fewer than three trials will be successful.
(A) 0.43
(B) 0.15
(C) 0.22
(D) 0.56
(E) 0.78
(A) 0.43
You want to create a 95% confidence interval with a margin of error of no more than 0.05 for a population proportion. The historical data indicate that the population has remained constant at about 0.55. What is the minimum size random sample you need to construct this interval?
(A) 378
(B) 380
(C) 223
(D) 324
(E) None of the above
(B) 380
A firm is hired by a small town to estimate the proportion of large trucks that are carrying hazardous materials on the main highway through the town. Of 350 randomly selected trucks, 92 were carrying hazardous materials. Is there evidence at the 10% level that the proportion of large trucks carrying hazardous materials is less than 30%?
(A) Yes, since the sample proportion is less than 30%.
(B) No, since the sample proportion is larger than 10%.
(C) Yes, since the p-value of the one-sided test is less than 10%.
(D) No, since the p-value of the one-sided test is less than 10%.
(E) The sample size is too small to make a determination.
(C) Yes, since the p-value of the one-sided test is less than 10%