Practice Final SU 2009

# Choose a card from a standard deck of 52 let a card

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25)Choose a card from a standard deck of 52. Let A = {card is red}; B = {card is a 2}; C = {card is a heart}. Which of the following pairs of events are NOT independent? a) Events A and B are NOT independent. b) Events A and C are NOT independent. c) Events B and C are NOT independent. d) All combinations of events are independent Use the following information for problems 26 – 28: As of 4:37 pm EST, 8/17/08, according to NBC, the individual medal count for the United States at the Olympics is shown in the table below. “Other” includes: cycling, equestrian, fencing, judo, shooting, wrestling. Swimmin g Gymnasti cs Track & Field Other Gold 12 1 0 6 Silver 9 3 1 8 Bronze 10 2 3 10 26)Select a medalist at random. What is the chance that they won a bronze medal and they were a swimmer? 5

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27)Given that an athlete won a Silver Medal, what is the chance that they were a gymnast? 28)Is the type of medal won, and sport performed in, independent of one another? a) Yes, they are independent b) No, they are not independent 29)In order to assess the effects of exercise on reducing cholesterol, a researcher sampled 50 people from a local gym who exercised regularly, and 50 people from the surrounding community who did not exercise regularly. They each reported to a clinic to have their cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of whether subjects exercised regularly or not. This is an example of: 30)The temperature at any random location in a kiln used in the manufacture of bricks is normally distributed with a mean of 1000 and a standard deviation of 50 °F. If bricks are fired at a temperature above 1124 °F, they will crack and must be disposed of. If the bricks are placed randomly throughout the kiln the proportion of bricks that crack during the firing process is: a) 99.34% b) 2.28% c) 47.72% d) 0.66% e) None of the Above 31) The professor of a large introductory statistics class thinks that her students spend 150 minutes per week studying for her class. A sample of 35 students reported in a questionnaire that they spent an average of 115 minutes per week studying statistics. Assume that the population standard deviation is σ x = 40 minutes. 6
a) Estimate the mean time spent studying statistics by students in this class with 95% confidence. Answer___________________ b) Does your confidence interval support her theory that her students spend 150 minutes per week studying for her class, or is she too optimistic? Circle one: Yes, her theory is supported No, she is too optimistic Briefly explain in one sentence: 32)Using the information from problem 31, suppose we want to estimate the mean time spent studying with 95% confidence, but we want a margin of error of no more than 9 minutes. What will our sample size need to be?

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• Winter '12
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