AP STAT chapter 6 quiz

Each entry in a table of random digits like Table D has probability 0.1 of being a 0, and the digits are independent of one another. Each line of Table D contains 40 random digits. The mean and standard deviation of the number of 0s in a randomly selected line will be approximately

• mean=0.1,

  standard deviation=0.05

• mean=0.1,

  standard deviation=0.1

•  mean=4, standard deviation=0.05

• mean=4, standard deviation=1.9

• mean=4, standard deviation=3.6

When a polling company calls a telephone number at random, there is only a 9% chance that the call reaches a live person and the survey is successfully completed. Suppose the random digit dialing machine makes 15 calls. Let X=the number of calls that result in a completed survey，What is the probability that more than 12 calls are not completed（give your answer 3 d.p.）

Suppose a student is randomly selected from your school. Which of the following pairs of random variables are most likely independent?

• X=student’s height; Y=student’s weight

• X=student’s IQ; Y=student’s GPA

• X=student’s PSAT Math score; Y=student’s PSAT Verbal score

• X=average amount of homework the student does per night; Y= student’s GPA

• X=average amount of homework the student does per night; Y=student’s height

A certain vending machine offers 20 ounce bottles of soda for $1.50. the number of bottles X bought from the machine on any day is a random variable with mean 50 and standard deviation 15. let the random variable Y equal the total revenue from this machine on a randomly selected day. Assume that the machine works properly and that no sodas are stolen from the machine. What are the mean and standard deviation of Y?

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• Normal, with mean 10 and standard deviation 1

• Normal, with mean 40 and standard deviation 2

• Normal, with mean 40 and standard deviation 4

• Binomal, with mean 40 and standard deviation 2

• Binomal, with mean 40 and standard deviation 4

which of the following random variables is geometric?

• the number of times I have to roll a single die to get two 6s

• the number of cards I deal from a well-shuffled deck of 52 cards to get a heart

• the number of digits I read in a randomly seected row of the random digits table to get 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.

Seventeen people have been exposed to a particular disease. Each one independently has a 40% chance of contracting the disease. A hospital has the capacity to handle 10 cases of the disease. What is the probability that the hospital's capacity will be exceeded?

• 0.011

• 0.035

• 0.092

• 0.965

• 0.989

a test for extrasensory perception(ESP) involves asking a person to tell which of 5 shapes-a sircle, star, triangle, diamond, or heart-appears on a hidden computer screen. On each trial, the computer is equally likely toselect any of the 5 shapes. Suppose researchers are testing a person who does not have ESP and so is just guessing on each trial. What is the probaility that the person guesses the first 4 shapes incorrectly but gets the fifth one correct?

• 1/5

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• 4/5

A psychologist studies the number of puzzles that subjects were able to solve in a 5-minute period while listening to soothing music. Let X be the number of puzzles completed successfully by a randomly chosen subject. The psychologist found that X had the following probability distribution: value of X are 1,2,3,4, and corresponding probability are 0.2, 0.4, 0.3, and 0.1 respectively. What is the probaility that a randomly chosen subject completes more than the expected number of puzzles in the 5-minute period while listening to soothing music?

• 0.1

• 0.4

• 0.8

• 1

• Cannot be determined

A psychologist studies the number of puzzles that subjects were able to solve in a 5-minute period while listening to soothing music. Let X be the number of puzzles completed successfully by a randomly chosen subject. The psychologist found that X had the following probability distribution: value of X are 1,2,3,4, and corresponding probability are 0.2, 0.4, 0.3, and 0.1 respectively. The standard deviation of X is 0.9. which of the following is the best interpretation of this value?

• about 90% of subjects solved 3 or fewer puzzles

• about 68% of subjects solved between 0.9 puzzles less and 0.9 puzzles more thean the mean

• the typical subject solved an average of 0.9 puzzles

• the number of puzzles solved by subjects typically differed from the mean by about 0.96 puzzles

• the number of puzzles solved by subjects typically differed from one another by about 0.9 puzzles.