AP Stat Semester

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

According to the U.S. Census, the proportion of adults in a certain county who owned their own home was 0.71. An SRS of 100 adults in a certain section of the county found that 65 owned their home. Which one of the following represents the approximate probability of obtaining a sample of 100 adults in which fewer than 65 own their home, assuming that this section of the county has the same overall proportion of adults who own their home as does the entire county?

• a

• b

• c

• d

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.

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

• A

• B

• C

• D

• E

Is this a probability distribution?

• No

• Yes

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

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

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.

The number of unbroken charcoal briquets in a 20-pound bag filled at the factory follows a Normal distribution with a mean of 450 briquets and a standard deviation of 20 briquets. The company expects that a certain number of the bags will be underfilled, so the company will replace for free the 5% of bags that have too few briquets. What is the minimum number of unbroken briquets the bag would have to contain for the company to avoid having to replace the bag for free?

• 404

• 418

• 411

• 425