AP Statistics Chapter 1-6 Review

A fast-food restaurant runs a promotion in which certain food items come with game pieces. According to the restaurant, 1 in 4 game pieces is a winner. If Jeff gets 4 game pieces, what is the probability that he wins exactly 1 price?

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Joe reads that 1 our of 4 eggs contains salmonella bacteria. So he never uses more than 3 eggs in cooking. If eggs do or don't contain salmonella independently of each other, the number of contaminated eggs when Joe uses 3 chosen at random has the following distribution:

• Binomial; n = 4 and p = 1/4

• Binomial; n = 3 and p = 1/4

• Binomial; n = 3 and p = 1/3

• Geometric; p = 1/4

• Geometric; p = 1/3

A binomial event has n = 60 trials. The probability of success on each trial is 0.4. Let X be the count of successes of the event during the 60 trials. What are mean X and standard deviation X?

• 24; 3.79

• 24; 14.4

• 4.9; 3.79

• 4.9; 14.4

Which of the following are discrete?

• I and III only

• II and III only

• I and IV only

• II and IV only

The probability of x, the number of tires needing replacement on a randomly selected automobile checked at a certain inspection station is given in the following table. What is the standard deviation of X?

• 1.2

• 2.52

• 1.58

The number of vehicles leaving a highway at a certain exit during a particular time period has a distribution that is approximately normal with mean value 500 and standard deviation 75. What is the probability that the number of cars exiting during this period is at least 650?

• 0.977

• 0.023

• 0.477

Which of the following random variables is geometric?

• The number of times I have to roll a die to get two 6s.

• The number of cards I deal from a well-shuffled deck of 52 cards until I get a heart.

• The number of digits I read in a randomly selected row of the random digits table until I find a 7.

• The number of 7s in a row of 40 random digits.

• The number of 6s I get if I roll a die 10 times.

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.
• No, all probabilities are not be between 0 and 1 inclusive
• No, the sum of all the probabilities is not 1.
• Yes, because the distribution is symmetric

• Yes, because all of the probabilities are between 0 and 1 inclusive and the sum of all the probabilities is 1.
• No, all probabilities are not be between 0 and 1 inclusive
• No, the sum of all the probabilities is not 1.
• Yes, because the distribution is symmetric

Suppose that a confidence interval for hours worked by students was computed to be (8.82, 10.78). Which of these is a valid interpretation of this confidence interval?

• There is a 95% probability that the average number of hours worked by all students is between 8.82 and 10.78 hours.

• There is a 95% probability that a randomly selected student worked between 8.82 and 10.78 hours.

• We are 95% confident that the population average number of hours worked by all students is between 8.82 and 10.78 hours.

• We are 95% confident that the average number of hours worked by the students in our sample is between 8.82 and 10.78 hours.