Assignment:
Q1: The NPC, Inc. is a large mail order company that ships men=s shirts all over the United States and Canada. They ship a large number of packages from their warehouse in Delta, Ohio. Their goal is to have 95 percent of the shipments delivered in 4 days. For many years they have used Brown Truck Inc., but recently there have been complaints about slow and inconsistent delivery. A sample of 10 recent shipments handled by Brown Truck showed a standard deviation in delivery time of 1.25 days. A sample of 16 shipments by Rapid Package Service showed a standard deviation in their delivery time of 0.45 days. At the 0.05 significance level is there more variation in the Brown Truck delivery time?
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic.
d. What is your decision regarding the null hypothesis? Interpret the result.
Q2. Jim Ray, an avid golfer, keeps records on his scores for 18 holes of golf. When the temperature is above 65 degrees, the standard deviation of his scores is 5.75 for 25 rounds. When the temperature is below 65 degrees, the standard deviation of his scores is 7.35 for a sample of 21 rounds. At the 0.05 significance level, is there more variation in his scores when the temperature is below 65 degrees?
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic.
d. What is your decision regarding the null hypothesis? Interpret the result.
Youngsville Northeast Corry
2.2 2.3 0.9
1.2 1.5 0.8
1.9 1.2 1.1
3.1 1.4 1.2
1.8 2.2 0.7
1.5
Q3. The County Executive for Monroe County is concerned about the response time for the three fire companies in the county. Samples of the response times (in minutes) for each company follow. At the 0.05 significance level is there a difference in the mean response time?
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic (use the tables).
d. What is your decision regarding the null hypothesis? Interpret the result.
Brand Weeks of Wear
A 3 4 6 3 4
B 2 3 2 5 2
C 5 7 5 4 6
Q4. A dentist is trying to decide if there is a difference in the number of weeks three different toothbrushes last. Fifteen patients were randomly assigned to three brands of toothbrushes and the number of weeks that the toothbrushes lasted is given. At the 0.05 significance level, is there a difference in the mean length of time the toothbrushes lasted?
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic.
Analysis of Variance
Source DF SS MS
Factor 2 16.93 8.47
Error 12 18.00 1.50
Total 14 34.93
d. What is your decision regarding the null hypothesis? Interpret the result.