AP Stat Unit 5 Review

Which one of the following would be a correct interpretation if you have a z-score of +2.0 on an exam?

• It means that you got twice as many questions correct as the average student.

• It means that your grade was 2 points higher than the mean grade on this exam.

• It means that your grade was in the upper 2% of all grades on this exam.

• It means that your grade is 2 standard deviations above the mean for this exam.

Records from a random sample of dairy farms yielded the information above on the number of male and female calves born at various times of the day.
What is the probability that a randomly selected calf was born in the night or was a female?

• 369/513

• 261/513

• 223/513

• 116/233

A grocery chain runs a prize game by giving each customer a ticket that may win a prize when the box is scratched off. Printed on the ticket is a dollar value ($500,$100, $25) or the statement “This ticket is not a winner.” Monetary prizes can be redeemed for groceries at the store. Here is the probability distribution above represents the amount won on a randomly selected ticket.
Which of the following are the mean and standard deviation, respectively, of the winnings?

• $15.00, $2900.00

• $15.00, $53.85

• $15.00, $26.93

• $156.25, $53.85

The five-number summary for a data set is given by min = 5, Q₁ = 18, median = 20, Q₃ = 40, max = 75. If you wanted to construct a boxplot for the data set (that is, one that would show outliers, if any existed), what would be the maximum possible length of the right-side “whisker”?

• 35

• 40

• 45

• 53

The probability distribution for the number of heads in four tosses of a coin is given above. The probability of getting at least one tail in four tosses of a coin is

• 15/16

• 4/16

• 1/16

• 14/16

In a certain large population of adults, the distribution of IQ scores is strongly left-skewed with a mean of 122 and a standard deviation of 5. Suppose 200 adults are randomly selected from this population for a market research study. The distribution of the sample mean of IQ scores is

• exactly Normal with mean 122 and standard deviation 5.

• exactly Normal with mean 122 and standard deviation 0.35.

• approximately Normal with mean 122 and standard deviation 5.

• approximately Normal with mean 122 and standard deviation 0.35.

Suppose we roll a fair die four times. The probability that a 6 occurs on exactly one of the rolls is

• 6(1/6)^2(5/6)^2

• 4(1/6)^1(5/6)^3

• 4(1/6)^3(5/6)^1

• 1(1/6)^0(5/6)^4

Social scientists are interested in the association between high school graduation rate (HSGR, measured as a percent) and the percent of U.S. families living in poverty (POV). Data were collected from all 50 states and the District of Columbia, and a regression analysis was conducted.The resulting least-squares regression line is given by POV-hat = 59.2 − 0.620(HSGR) with r² = 0.802. Based on the information, which of the following is the best interpretation for the slope of the least-squares regression line?

• For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.620.

• For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.896.

• For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to increase by approximately 0.620.

• For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.802.

Based on the shape of this distribution, what measures of center and spread would be most appropriate to report?

• The mean and standard deviation

• The mean and the interquartile range

• The median and the standard deviation

• The median and the interquartile range

The correlation between the age and height of children under the age of 12 is found to be r = 0.60. Suppose we use the age x of a child to predict the height y of the child. What can we conclude?

• The height is generally 60% of a child’s weight.

• About 60% of the time, age will accurately predict height.

• Thirty-six percent of the variation in height is accounted for by the linear model relating height to age.

• For every 1 year older a child is, the regression line predicts an increase of 0.6 feet in height.