chapter 1
You record the age, marital status, and earned income of a sample of 1463 women. The number and type of variables you have recorded is
A. 3 quantitative, 0 categorical.
B. 3 quantitative, 1 categorical.
C. 2 quantitative, 1 categorical.
D. 2 quantitative, 2 categorical.
C. 2 quantitative, 1 categorical
Many professional schools require applicants to take a standardized test. Suppose that 1000 students take such a test. Several weeks after the test, Pete receives his score report: he got a 63, which placed him at the 73rd percentile. This means that:
A. Pete did worse than about 63% of the test takers.
B. Pete did worse than about 73% of the test takers.
C. Pete did better than about 63% of the test takers.
D. Pete did better than about 73% of the test takers.
D. Pete did better than about 73% of the test takers.
Which of the following statements is not true of the correlation r between the length in inches and weight in pounds of a sample of brook trout?
A. r must take a value between −1 and 1.
B. r is measured in inches.
C. If longer trout tend to also be heavier, then r > 0.
D. r would not change if we measured the lengths of the trout in centimeters instead of inches.
B. r is measured in inches.
Which one of the following is a valid statistical question?
A. How tall is the Empire State Building?
B. How many points did LeBron James score in the 2018 NBA playoffs?
C. When you call your cell-phone provider’s customer service number, how long will you typically be on hold?
D. How much money did Ivan’s family spend on groceries last month?
C. When you call your cell-phone provider’s customer service number, how long will you typically be on hold?
Dr. Stats plans to toss a fair coin 10,000 times in the hope that it will lead him to a deeper understanding of the laws of probability. Which of the following statements is true?
A. It is unlikely that Dr. Stats will get more than 5000 heads.
B. Whenever Dr. Stats gets a string of 15 tails in a row, it becomes more likely that the next toss will be a head.
C. The chance that the 100th toss will be a head depends somewhat on the results of the first 99 tosses.
D. It is likely that Dr. Stats will get about 50% heads.
D. It is likely that Dr. Stats will get about 50% heads.
For which of the following variables would it be more appropriate to use a bar chart than a histogram to display the distribution?
A. Annual income
B. Number of pets
C. Age
D. Marital status
D. marital status
Which of the following is closest to the 28th percentile of the standard normal distribution?
A. z=-0.58
B. z=-0.50
C. z=0.39
D. z=0.61
A. z=-0.58
In a certain population there is an approximately linear relationship between height of females (in centimeters) and X = their age (in years, from 5 to 18) described by the equation ŷ = 50.3 + 6.1x. Which one of the following statements must be true?
A. The estimated slope is 6.1, which implies that girls in this population between the ages of 5 and 18 are predicted to grow about 6.1 centimeters in height for each year they grow older.
B. The estimated intercept is 50.3 centimeters. We can conclude from the intercept that the typical height of girls in this population at birth is 50.3 centimeters.
C. A 10-year-old girl in this population is at least 110.3 centimeters tall.
D. One particular 8-year-old girl is 115 centimeters tall. She is shorter than expected for girls her age in this population.
A. The estimated slope is 6.1, which implies that girls in this population between the ages of 5 and 18 are predicted to grow about 6.1 centimeters in height for each year they grow older.
Some news organizations maintain a database of customers who have volunteered to share their opinions on a variety of issues. Suppose that one of these databases includes 9000 registered voters in California. To measure the amount of support for a controversial ballot issue, 1000 registered voters in California are randomly selected from the database and asked their opinion. Which of the following is the largest population to which the results of this survey should be generalized?
A. The 1000 people in the sample
B. The 9000 registered voters from California in the database
C. All registered voters in California
D. All California residents
B. The 9000 registered voters from California in the database
When three-digit telephone area codes were first put in place in the United States and Canada, the first number could be any digit from 2 through 9, the second number could only be 0 or 1, and the third number could be any digit from 0 through 9. How many possible area codes can be created with this format?
A. 24
B. 126
C. 140
D. 160
D. 160
The mean speed of vehicles in the “cars only” lanes of the New Jersey turnpike is 68 mph. The mean speed of vehicles in the “any vehicle” lanes is 64 mph. What must be true about the mean speed of all vehicles on the turnpike, assuming these are the only types of lanes?
A. It could be any number from 64 to 68 mph.
B. It must be larger than the median speed.
C. It must be larger than 66 mph.
D. It must be 66 mph.
A. It could be any number from 64 to 68 mph.
Scores on the ACT college entrance exam can be modeled using a normal distribution with mean 21 and standard deviation 5. Wayne’s standardized score on the ACT was . What was Wayne’s actual ACT score?
A. 3
B. 13
C. 16
D. 18
D
The percent of the variation in the values of y that is accounted for by the least-squares regression of y on x is
A. the correlation.
B. the slope of the least-squares regression line.
C. the square of the correlation.
D. the standard deviation of the residuals.
C. the square of the correlation.
A local news agency conducted a survey about unemployment by randomly dialing phone numbers until it had gathered responses from 1000 adults in the state. In the survey, 19% of those who responded said they were not currently employed. In reality, only 6% of the adults in the state were not currently employed at the time of the survey. Which of the following best explains the difference in the two percentages?
A. The difference is due to sampling variability. We shouldn’t expect the results of a random sample to match the truth about the population every time.
B. The difference is due to response bias. Adults who are employed are likely to lie and say that they are unemployed.
C. The difference is due to undercoverage. The survey included only adults and did not include teenagers who are eligible to work.
D. The difference is due to nonresponse. Adults who are employed are less likely to be available for the sample than adults who are unemployed.
D. The difference is due to nonresponse. Adults who are employed are less likely to be available for the sample than adults who are unemployed.
There are 12 students running for three student council positions: president, vice president, and secretary. Which of the following expressions represents the number of ways in which these three positions can be filled by the 12 candidates?
A. 12*12*12
B. 12*11*10
C. (12*11*10) divided by (3*2*1)
D. 12!
B. 12*11*10