Exam 8: Regression, Associations, and Predictive Modeling

Which type of plot would be most appropriate to display the responses to type of residence?

At www.census.gov you can create a "population pyramid" for any country. These pyramids are back-to-back histograms. This pyramid shows Mexico's 2000 female population and the census bureau's projection for 2050. Write a few sentences summarizing the changes that are forecast.

Adult female Dalmatians weigh an average of 50 pounds with a standard deviation of 3.3 pounds. Adult female Boxers weigh an average of 57.5 pounds with a standard deviation of 1.7 pounds. One statistics teacher owns an underweight Dalmatian and an underweight Boxer. The Dalmatian weighs 45 pounds, and the Boxer weighs 52 pounds. Which dog is more underweight? Explain.

A company's sales increase by the same amount each year. This growth is . . .

Is there evidence of an association between high school and first-year college GPAs? Test an appropriate hypothesis and state your conclusion in the proper context.

Variables X and Y have r = 0.40. If we decrease each X value by 0.1, double each Y value, and then Interchange them (put X on the Y-axis and vice versa) the new correlation will be

The city council has 6 men and 3 women. If we randomly choose two of them to co-chair a Committee, what is the probability these chairpersons are the same gender?

Salary conversions You learn that your company is sending you and several other employees to staff a new office in China. While there everyone will earn the equivalent of their current salary, converted to Chinese currency at the rate of 8 yuans per dollar. In addition, everyone will earn a weekly foreign living allowance of 200 yuans. For example, since you are earning $1000 per week, your weekly salary in China will be 1000 x 8 + 200 = 8200 yuans. a. Shown are some summary statistics describing the current salaries of this group being sent overseas. Fill in the table to show what these statistics will be for the salaries you all will earn while in China. Statistic In the US In China Minimum salary \ 400 Standard deviation \ 250 Median \ 750 IQR \ 300 b. Among this group of employees going to China, your US salary has a $z - s c o r e \text { of } + 1.20$ What will your new z-score be, based on everyone's China salary?

We have calculated a 95% confidence interval and would prefer for our next confidence interval to Have a smaller margin of error without losing any confidence. In order to do this, we can I. change the z value to a smaller number. II. take a larger sample. III. take a smaller sample.

Interpret the slope in context.

Associations For each pair of variables, indicate what association you expect: positive(+), negative(-), curved(C), or none(N). a. power level setting of a microwave; number of minutes it takes to boil water b. number of days it rained in a month (during the summer); number of times you mowed your lawn that month c. number of hours a person has been up past a normal bedtime; number of minutes it takes the person to do a crossword puzzle d. number of hockey games played in Minnesota during a week; sales of suntan lotion in Minnesota during that week e. length of a student's hair; number of credits the student earned last year

For purposes of making budget plans for staffing, a college reviewed student's year in school and area of study. Of the students, 22.5% are seniors, 25% are juniors, 25% are sophomores, and the rest are freshmen. Also, 40% of the seniors major in the area of humanities, as did 39% of the juniors, 40% of the sophomores, and 36% of the freshmen. What is the probability that a randomly selected humanities major is a junior? Show your work.

Soft drinks A restaurant owner wanted to improve the efficiency of his employees. One way he tried to do this was to buy a machine that will automatically dispense 16 oz. of soda into a glass rather than have the employee hold the button on the dispenser. The actual amount dispensed by the machine can be represented by the model N(16.2, 0.3) a. Draw and clearly label the model. b. The sales representative who sold him the machine said, "95% of the glasses you fill with soda will fall between _________ and _________." Fill in the blanks based on the normal model, then comment on this claim. c. What is the 3rd quartile of amounts dispensed? d. If a glass will actually hold 16.7 oz. of soda, what percent of the time would you expect the glass to overflow? e. The manufacturer wants to reduce the overflow rate to only 1%. Assuming the mean amount dispensed will stay the same, what standard deviation must they achieve? f. Briefly explain what that change in standard deviation means in this context. g. A competing manufacturer says that not only will 98% of their glasses be safe from overflowing, but 70% will have more than 16 oz., reducing customer complaints. What Normal model parameters is that manufacturer claiming? Show your work.

Which of these variables is most likely to be bimodal?

An ice cream stand reports that 12% of the cones they sell are "jumbo" size. You want to see what a "jumbo" cone looks like, so you stand and watch the sales for a while. What is the probability that The first jumbo cone is the fourth cone you see them sell?

Given that a randomly selected bike has a kickstand, what are the chances that it also has a water Bottle holder?

The two samples whose statistics are given in the table are thought to come from populations with Equal variances. What is the pooled estimate of the population standard deviation? n Mean SD 12 45 6 16 41 8

Peanut M&Ms According to the Mars Candy Company, peanut M&M's are 12% brown, 15% yellow, 12% red, 23% blue, 23% orange, and 15% green. On a Saturday when you have run out of statistics homework, you decide to test this claim. You purchase a medium bag of peanut M&M's and find 39 browns, 44 yellows, 36 red, 78 blue, 73 orange, and 48 greens. Test an appropriate hypothesis and state your conclusion.

Match each graph with the appropriate correlation coefficient. ______ $0.98$ _____ $0.73$ _____- $0.09$ ______ $-0.99$ A. B. C. D.

A medical researcher finds that the more overweight a person is, the higher his pulse rate tends to Be) In fact, the model suggests that 12-pound differences in weight are associated with differences In pulse rate of 4 beats per minute. Which is true? I. The correlation between pulse rate and weight is 0.33 II. If you lose 6 pounds, your pulse rate will slow down 2 beats per minute. III. A positive residual means a person's pulse rate is higher than the model predicts.