AP Statistics Review #7

1. Which of the following statements are true?I. Sample parameters are used to make inferences about population statistics.II. Statistics from smaller samples have more variability.III. Parameter are fixed, while statistics vary depending on which sample is chosen.(A)I and II(B) I and III(C)II and III(D)I, II, and III(E) None of the above gives the complete set of true responses.

2. Each of the 29 NBA teams has 12 players. A sample of 58 players is to be chosen asfollows. Each team will be asked to place 12 cards with their players’ names into a hatand randomly draw out two names. The two names from each team will be combined tomake up the sample. Will this method result in a simple random sample?(A)Yes, because each player has the same chance of being selected.(B) Yes, because each team is equally represented.(C)Yes, because this is an example of stratified sampling, which is a special case of simplerandom sampling.(D)No, because the teams are not chosen randomly(E) No, because not each group of 58 player has the same chance of being selected.

3. Data are obtained for a group of college freshman examining their SAT scores (mathplus verbal) from their senior year of high school and their GPA’s during their first yearof college. The resulting regression equation isWhat percentage of the variation in GPA’s can be explained by looking at SAT scores?(A)0.0161%(B) 16.1%(C)39.9%(D)63.2%(E) This value cannot be computed from the information given.

4. Suppose you will be taking exams in English, Statistics and Physics tomorrow, and frompast experience you know that for each exam you have a 60% chance of receiving an A. Listall eight possibilities for receiving A’s on the various exams. Letting X represent the numberof A’s you will receive, show the probability distribution table for X.

5. Suppose that your rival in the marketing department has what you consider a dumbidea. Your boss, who knows nothing about statistics, is relatively conservative but willfollow up on this dumb idea if there is good evidence that more than 25% of the company’scustomers like it. A survey of 40 customers is taken, and 12 of them favor the idea. Yourrival points out that 12/40 is 30%. You know a little about statistics and perform the usualhypothesis test with. Perform a complete significance testand write a few sentences about the conclusion for your boss as to why these data are notstrong evidence that more than 25% of the customers like your rival’s idea.