Unit Test Answers

Josie believes that her mom calls her at the most inconvenient times. As a matter of fact, Josie thinks that 80% of the times that her mom calls, she is busy doing important tasks such as schoolwork, driving, or feeding the family pets.Which is the best interpretation of this probability?

A three-digit personal identification number is chosen using the digits 1–9. The digits cannot be repeated.What is the approximate probability that the first digit will be 6?

A librarian has 10 nonfiction and eight fiction books from which to choose the next three book club selections.What is the approximate probability that she chooses a fiction book, then a nonfiction book, then a fiction book?

The following two-way table shows the distribution of weekend work hours and how long employees have been at the company.

Four girls and six boys are in a Spanish club. Three of the people will be chosen at random to represent the group in a photograph.What is the probability that one girl and two boys will be chosen?

An airline claims that 80% of adults have flown at least once. From a sample of 20 teenagers it is found that only 13 have flown at least once, giving reason to believe that the true parameter for teens is less than 80%.Let 0–7 represent having flown at least once (F) and let 8–9 represent never having flown (N).

A researcher randomly selected 132 high school students and asked them about their study habits and lighting preference when studying. The two-way table displays the data. Suppose one of the students is randomly selected. Let L = the student prefers low light and S = the student sometimes studies.Which of the following is the correct value and interpretation of P(S|L)?

A recent survey found that 80% of jeans have back pockets, 65% have front pockets, and 48% have both back and front pockets. Suppose a pair of jeans is selected at random and it is determined that it has front pockets. What is the probability that a randomly selected pair of jeans with front pockets also has back pockets?

At a high school, students can choose between three art electives, four history electives, and five computer electives. Each student can choose two electives.What is the approximate probability that a student chooses a computer elective and an art elective?

A bag contains 10 red marbles, 15 yellow marbles, 5 green marbles, and 20 blue marbles. Two marbles are drawn from the bag.Which expression represents the probability that one of the marbles is red and the other is blue?

A medical researcher claims that 60% of people with shellfish allergies do not have their first allergic reaction until adulthood. This value seems suspicious to a class of statistics students, so they ask an SRS of 30 adults with a shellfish allergy when they experienced their first allergic reaction. Fourteen of the adults experienced their first allergic reaction in adulthood. To see if this result is surprising, the class conducts a simulation to estimate the probability of obtaining a sample result as low as the one in their sample.Let 0–5 represent "adulthood” and 6–9 represent "before adulthood.”Using the line of random numbers, how many "adulthood” responses are in the first trial of the simulation?

The following two-way table shows the distribution of a random sample of travelers and their preferences for accommodations and method of travel.

A certain dog can catch a properly thrown tennis ball with a probability of 0.95. Unfortunately, this dog has dropped the last six properly thrown tennis balls. The owner explains that the next throw has to be caught by the dog because he never misses this many.