AP Stats CH3 Review

The student government at a high school wants to conduct a survey of student opinion. It wants to begin with a simple random sample of 80 students. Which of the following survey methods will produce a simple random sample?

• Survey the first 80 students to arrive at school in the morning

• Survey every 5th student entering the school library until 80 students are surveyed.

• Use random numbers to choose 20 each of first-year, second-year, third-year, and fourth-year students.

• Number the students in the official school roster. Use a table of random numbers to choose 80 students from this roster for the survey.

• Number the cafeteria seats. Use a table of random numbers to choose seats and interview the students until 80 have been interviewed.

A cosmetics supplier ships boxes of highlighter to individual customers. The distribution of weights of shipped boxes is approximately normal with mean 5 pounds and standard deviation 1.2 pounds. Which expression represents the weight, in pounds, at the 75th percentile of the distribution?

• -1.96(1.2) + 5

• -0.25(1.2) + 5

• 0.25(1.2) + 5

• 0.67(1.2) + 5

• 0.75(1.2) + 5

The boxplots summarize two data sets, 1 and 2. Which of the following must be true?

• I only

• I and III only

• I and II only

• I, II, and III

• III only

Use the table to answer the following question. Of the male subjects in the study, what fraction drive a sports car?

• 39/84

• 39/240

• 39/60

• 60/240

• 84/240

A friend has placed a large number of plastic disks in a hat and invited you to select one at random.  He informs you that half are red and half are blue.  If you draw a disk, record the color, replace it, and repeat 100 times, which of the following is true?

• It is unlikely you will choose red more than 50 times.

• If you draw 10 blue disks in a row, it is more likely you will draw a red on the next try.

• The overall proportion of red disks drawn should be close to 0.50.

• The chance that the 100th draw will be red depends on the results of the first 99 draws.

A die is loaded so that the number 6 comes p three times as often as any other number.  What is the probability of rolling a 4, 5, or 6?

• 2/3

• 1/2

• 5/8

• 1/3

A dealer in Las Vegas selects 10 cards from a standard deck of 52 cards.  Let Y be the number of diamonds in the 10 cards selected.  Which of the following best describes this setting?

• Y has a binomial distribution with n = 10 observations and probability of success p = 0.25.

• Y has a binomial distribution with n = 10 observations and probability of success p = 0.25, provided the deck is shuffled well.

• Y is a binomial distribution with n = 10 observations and probability of success p = 0.25, provided that after selecting a card it is replaced in the deck and the deck is shuffled well before the next card is selected.

• Y has a geometric distribution with n = 10 observations and probability of success p = 0.25

It is known that about 90% of the widgets made by Buckley Industries meet specifications.  Every hour a sample of 18 widgets is selected at random for testing and the number of widgets that meet specifications is recorded.  What is the approximate mean and standard deviation of the number of widgets meeting

• μ = 1.62; σ = 1.414

• μ = 1.62; σ = 1.265

• μ = 16.2; σ = 1.62

• μ = 16.2; σ = 1.273

Le the random variable X represent the amount of money Carl makes tutoring statistics students in the summer.  Assume that X is Normal with mean $240 and standard deviation $60.  The probability is approximately 0.6 that, in a randomly selected summer, Carl will make less than about

• $144

• $216

• $255

• $30

The time it takes students to complete a statistics quiz has a mean of 20.5 minutes and a standard deviation of 15.4 minutes.  What is the probability that a random sample of 40 students will have a mean completion time greater than 25 minutes?

• 0.9678

• 0.0322

• 0.0344

• 0.3851