Business Analytics I
Exam #2Antony Davies, Ph.D.
Summer 2009June 3, 2009
This exam is due at the start of class on Wednesday, June 3, 2009.
You may work on this exam alone, or you may work in a group of no more than two people. If you work in a group, submit only one copy of the exam answers.
Sources you may consult in completing the exam:
- A calculator.
- Excel (including the probabilities worksheet I provided).
- Your text.
- Your notes.
- Past assignments and answers (from the website).
Instructions
- You may not consult any sources other than those listed above.
- Unless told otherwise, do not use information from one question to answer another.
- Report your answers on the answers sheet. Write your answer in the space provided. Where applicable, show your work in the space provided.
- Do not provide additional verbal qualifications to your answers. If you feel the need to explain why your answer is correct or conditions under which your answer is correct, then your answer is likely incorrect.
- Prior to the start of class on the due date, hand in this page and the answer sheets. Exams not handed in by the start of class receive grades of zero.
Please affirm your agreement with the following statement by signing after you complete the exam.
In accordance with Duquesne’s honor code, I attest that I neither received nor offered unauthorized assistance in answering the questions on this exam. If I am a member of a team, I further attest that I have seen and agree with the contribution ratings shown above, and that I have seen and agree with the exam answers my team has submitted.
Name(s):______
On these pages, write your final answer and then show all of your work.
Question #1Answer______
Work
Question #2Answer______
Work
Question #3Answer______
Work
Question #4Answer______
Work
Question #5Answer______
Work
Question #6Answer______
Work
Question #7Answer______
Work
Question #8Answer______
Work
Question #9Answer______
Work
Question #10Answer______
Work
Question #11Answer______
Work
Question #12Answer______
Work
Questions 1 through 3 refer to the scenario below.
The weight of football players is normally distributed with a population mean of 200 pounds and a population standard deviation of 25 pounds.
1.What is the probability of a randomly selected player weighing more than 250 pounds?
2.What is the probability of a randomly selected player weighing less than 175 pounds?
3.What proportion of players weighs between 180 and 220 pounds?
Questions 4 through 6 refer to the scenario below.
The starting salaries of individuals with an undergraduate degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000.
4.What is the probability that a randomly selected individual with an undergraduate degree will get a starting salary of at least $30,000?
5.What is the probability that a randomly selected individual with an undergraduate degree will get a starting salary of at least $55,000?
6.What proportion of undergraduates will have starting salaries between $35,000 and $45,000?
7.One-hundred randomly selected people are asked if they favor penalties for drivers who do not wear seatbelts. Eighty of the people in the sample favored penalties. What is the 95% confidence interval for the true proportion of people who favored penalties?
8.The proprietor of a boutique in New York wants to determine the average age of his customers. A random sample of 25 customers reveals an average age of 28 years with a standard deviation of 10 years. What is the 95% confidence interval for the average age of all his customers?
9.A random sample of 16 patients in a doctor’s office had to wait an average of 35 minutes with a standard deviation of 15 minutes before they could see the doctor. What is the 90% confidence interval for the average waiting time of all the patients who visit this doctor? Assume the population of waiting times is normally distributed.
10.A random sample of 16 patients in a doctor’s office had to wait an average of 35 minutes with a standard deviation of 15 minutes before they could see the doctor. What is the 90% confidence interval for the waiting time of a randomly selected patient who visits this doctor? Assume the population of waiting times is normally distributed.
11.A coffee packing firm must closely monitor the amount of coffee that goes into its cans. If too much coffee goes in, the firm’s costs of production rise. If too little coffee goes in, the firm risks lawsuits and bad publicity from disgruntled customers. The firm’s quality control people take a sample of 35 cans and weigh the contents of each can. The sample reveals a mean of 11.8 ounces with a standard deviation of 0.5 ounces. Test to see if the population mean is equal to the advertised 12 ounces. Test the hypothesis, H0: μ = 12 vs. HA: μ ≠ 12. What is the p-value for this test?
12.A credit card company has determined that the breakeven point for maintaining a credit card customer is a customer balance of $1,150. The company is considering marketing its credit card to college students in the Pittsburgh area. To this end, the firm has surveyed 30 students in the Pittsburgh area. The survey shows an average credit card balance (per student) of $1,200 with a standard deviation of $126. You want to determine if the population mean of student account balances is greater than $1,150. Test the hypothesis, H0: μ ≥ 1,150 vs. HA: μ < 1,150. What is the p-value for this test?