The following data are the monthly salaries y and the grade point averages x for students who obtained a bachelor's degree in business administration.

The estimated regression equation for these data is y^ = -464.3 + 1285.7x and MSE = 259,464

a. Develop a point estimate of the starting salary for a student with a GPA of 3.0 (to 1 decimal).
  

b. Develop a  confidence interval for the mean starting salary for all students with a 3.0 GPA (to 2 decimals).

(  ,   )

c. Develop a  prediction interval for Ryan Dailey, a student with a GPA of 3.0 (to 2 decimals).

(  ,   )

The students in one college have the following rating system for their professors:excellent, good, fair, and bad. In a recent poll of the students, it was found that they believe that 20% of the professors are excellent, 50% are good, 20% are fair, and 10% are bad. Assume that 12 professors are randomly selected from the college.
a. What is the probability that 6 are excellent, 4 are good, 1 is fair, and 1 is bad?
b. What is the probability that 6 are excellent, 4 are good, and 2 are fair?
c. What is the probability that 6 are excellent and 6 are good?
d. What is the probability that 4 are excellent and 3 are good?
e. What is the probability that 4 are bad?
f. What is the probability that none is bad?

Hypothesis Tests with Z-statistics

Students in a physics class have an average of 73 on exams with a standard deviation of 12. The teacher is testing a whether having open book exams will help her students get better scores. After 6 open book exams, her class has an average of 76.5 on the exams.

a. Who are the groups being compared/tested?
b. What are the null and research hypotheses?
c. what are the numbers needed for the z statistic?
d. What is the z statistic?
e. For a two tailed test at .05 significance, the critical area is +/- 1.96. What decision do we make?

Students in a seventh-grade class were given an exam. During the next 2 years, the same students were retested several times. The average score g can be approximated by the model

g(t) = 81 − 13 log₁₀(t + 1),    0 ≤ t ≤ 24

where t is the time (in months).

(a) What was the average score on the original exam? ???


(b) What was the average score after 6 months? (Round your answer to one decimal place.) ???


(c) When did the average score drop below 70? (Round your answer to the nearest month.)

The average score dropped below 70 after ??? months.

1.Sixteen students choose exactly one snack each from three different snacks offered after class. On a given day, what is the probability that 8 students choose fruit, 5 choose yogurt and the rest choose power bars?

2. A book shelf has nine books. Five of the books have identical red covers and four have identical white covers.

a. In how many ways can 3 red and 3 white books be chosen from the nine books?

b. You select 4 books from the shelf. What is the probability of selecting exactly 4 books of the same color?

For which of the following scenarios would it be appropriate to use a one-sample z-test?

A. Comparing the average weight of newborns in Hospital A to the average weight of newborns in Hospital B

B. Comparing the political affiliation of ASU students against the political affiliation of all college students

C. Comparing the number of packs of cigarettes smoked per day by residents of urban areas with the number of cigarettes smoked per day by all persons in the USA

D. All of the above

E. Comparing the results of Likert scale patient satisfaction scores of patients at the VA against the Likert scale patient satisfaction scores of the overall population of patients

The time needed for college students to complete a certain paper-and-pencil maze follows a normal distribution with a mean of 30 seconds and a standard deviation of 2 seconds. You wish to see if the mean time μ is changed by vigorous exercise, so you have a group of 20 college students exercise vigorously for 30 minutes and then complete the maze. It takes them an average of x¯=27.2 seconds to complete the maze. Use this information to test the hypotheses H0:μ=30 Ha:μ≠30 Conduct a test using a significance level of α=0.01. (a) The test statistic (b) The positive critical value, z =

By some estimates, thirty-­‐percent (30%) of all students in Groningen go on ski vacation each year. Out of a random sample of 300 students, what is the approximate probability that more than 100 of them went to ski this year? (Use the normal approximation)

And:

Oscar is getting married in Brazil where it rains only 1% of the time. Unfortunately, the weather expert has predicted rain for tomorrow. On a given day, there is a 9% chance that the weather expert predicts rain. 90% of the time that the weather expert has forecasted rain, it does in fact rain. What is the probability that it will rain on the day of Oscar´s wedding?

Suppose you are interested in knowing the average cholesterol level of all women between the ages of 21 and 30 who live in College Station. Everyone in a class (100 students) takes a random sample of 50 females in the College Station area between the ages of 21 and 30. Each student calculates the average cholesterol in their sample. Jenna is one of the students in this class and she makes a histogram of the 50 cholesterol levels in her sample. What kind of distribution would be displayed in Jenna's histogram?

7.38 Teaching descriptive statistics. A study compared five different methods for teaching descriptive statistics. The five methods were traditional lecture and discussion, programmed textbook instruction, programmed text with lectures, computer instruction, and computer instruction with lectures. 45 students were randomly assigned, 9 to each method. After completing the course, students took a 1-hour exam. (a) What are the hypotheses for evaluating if the average test scores are different for the different teaching methods? (b) What are the degrees of freedom associated with the F-test for evaluating these hypotheses? (c) Suppose the p-value for this test is 0.0168. What is the conclusion?