Exam 8: Regression, Associations, and Predictive Modeling

Approval rating A newspaper article reported that a poll based on a sample of 1150 residents of a state showed that the state's Governor's job approval rating stood at 58%. They claimed a margin of error of ±3%. What level of confidence were the pollsters using?

Shoot You and a friend are working on shooting free throws at basketball practice. Your friend has a season average of making 80% of his shots. a. If the coach asks your friend to shoot 70 times, how many shots do you expect him to make, on average? b. What is the standard deviation of the number of shots made out of 70? c. Your friend makes 60 out of 70 shots and is ready to tell the coach that he is improving. The graph below shows a simulation of this distribution. Using both your answers to (a) and (b) and this graph, explain whether or not the coach should have confidence in his improvement.

A wildlife biologist wants to determine the mean weight of adult red squirrels. She captures 10 Squirrels she believes to be representative of the species and weighs them, finding a mean of 12.32 Grams and standard deviation of 1.88 gm. Assuming these squirrels can be considered a random Sample of all red squirrels which of the following formulas gives a 95% confidence interval for the Mean weight of all squirrels?

It was discovered that a larger proportion of children who slept with nightlights later developed Nearsightedness, compared to children who did not sleep with nightlights. The headlines read, "Leaving a light on for you children causes nearsightedness!" Later it was pointed out that Nearsighted people have more trouble seeing in the dark and are more likely to leave lights on at Night for their kids. And those same nearsighted parents are likely to have nearsighted kids. This is An example of

A professor was curious about her students' grade point averages (GPAs). She took a random Sample of 15 students and found a mean GPA of 3.01 with a standard deviation of 0.534. Which of The following formulas gives a 99% confidence interval for the mean GPA of the professor's Students?

Five

The correlation coefficient between the hours that a person is awake during a 24-hour period and The hours that same person is asleep during a 24-hour period is most likely to be

lower scores if they also were athletes. Assuming that this group of students is representative of students throughout the state, what do you think? -Test an appropriate hypothesis and state your conclusion.

Scrubbers A factory recently installed new pollution control equipment ("scrubbers") on its smokestacks in hopes of reducing air pollution levels at a nearby national park. Randomly timed measurements of sulfate levels (in micrograms per cubic meter) were taken before (Set C1) and after (Set C2) the installation. We believe that measurements of sulfate levels are normally distributed. Write a complete conclusion about the effectiveness of these scrubbers based on the statistical software printout shown.

Six Republicans and four Democrats have applied for two open positions on a planning committee. Since all the applicants are qualified to serve, the City Council decides to pick the two new Members randomly. What is the probability that both come from the same party?

In the study "The Role of Sports as a Social Determinant for Children," student respondents in grades 4 through 6 were asked what they would most like to do at school: make good grades, be popular or be good at sports. Results delineated by type of school district are reported below. Rural Suburban Urban Make Good Grades 57 87 24 Be Popular 50 42 6 Be Good at Sports 42 22 5 Source: Chase, M.A and Dummer, G.M. (1992), "The Role of Sports as a Social Determinant for Children," Research Quarterly for Exercise and Sport, 63, 418-424. Is there evidence that type of school district and personal school goals are independent? Test an appropriate hypothesis. Give Statistical evidence to support your conclusion.

Twenty dogs and 20 cats were subjects in an experiment to test the effectiveness of a new flea Control chemical. Ten of the dogs were randomly assigned to an experimental group that wore a Collar containing the chemical, while the others wore a similar collar without the chemical. The Same was done with the cats. After 30 days veterinarians were asked to inspect the animals for fleas And evidence of flea bites. This experiment is…

What is the probability that exactly 3 of the first 10 customers buy specialty clothes for their pet? Show work.

When two competing teams are equally matched, the probability that each team wins any game is 0.5. The NBA championship goes to the team that wins four games in a best-of seven series. If the teams were equally matched, the probability that the final series ends with one of the teams sweeping four straight games would be 2 $2 ( 0.5 ) ^ { 4 } = 0.125 . \text { Further }$ probability calculations indicate that 25% of these series should last five games, 31.25% should last six games, and the other 31.25% should last the full seven games. The table shows the number of games it took to decide each of the last 57 NBA champs. Do you think the teams are usually equally matched? Give statistical evidence to support your conclusion. Length of series 4 games 5 games 6 games 7 games NBA finals 7 13 22 15

List the variables. Indicate whether each variable is categorical or quantitative. If the variable is quantitative, tell the units.

Explain why the last plan suggested above, selecting the ten trees closest to the parking lot, might be biased. Be sure to name the kind(s) of bias you describe and link it to the variable of interest.

Find each percent. a) What percent of the students are girls who ride the bus? b) What percent of the girls ride the bus? c) What percent of the bus riders are girls?

Suppose that the student taking 22 credit hours in the data set was actually taking 28 credit hours instead of 22 (so we would replace the 22 in the data set with 28). Indicate whether changing the number of credit hours for that student would make each of the following summary statistics increase, decrease, or stay about the same: a. mean b. median c. range d. IQR e. standard deviation

How many blood donors should the American Red Cross expect to collect from until it gets a donor with Type B blood?

Which of the W's are unknown for these data?