Reference no: EM132292231

Statistics for Business Assignment - Exercises

Part A -

Exercise 1) A recent Time magazine reported the following information about the weekly work load of workers in Germany and the United States:

	Sample Size	Mean	Standard Deviation
US	60	42	5
Germany	70	38	6

At 5% level, test to determine whether or not there is a significant difference between the average workweek in the United States and the average workweek in Germany.

Exercise 2) A random sample of 36 tourists in the Grand Bahamas showed that they spent an average of $1,750 (in a week) with a standard deviation of $125; and a sample of 25 tourists in New Province showed that they spent an average of $1,900 (in a week) with a standard deviation of $130. At 5% significance level, do the data indicate that tourists who visited New Province spent, on average, $100 more than those who visited the Grand Bahamas? State any assumptions you've made to do this problem.

Exercise 3) A firm is studying the delivery times for two raw material suppliers. In this regards random samples of delivery times of the 2 suppliers were collected (Delivery times worksheet).

a) Does the data suggest that the mean delivery times of supplier B is less than that of supplier A? Use a 1% significance level.

b) Find a 99% confidence interval for the difference between the mean delivery times of suppliers A and B.

Exercise 4) A consumer agency wants to compare the caffeine content of two brands of coffee. Eight jars of each brand are analyzed, and the amount of caffeine found in each jar is recorded as shown in the table (Caffeine data).

Brand I	82	77	85	73	84	79	81	82
Brand II	75	80	76	81	72	74	73	78

Using α = 0.10, can you conclude that the two brands have different median caffeine contents per jar?

Exercise 5) In an effort to increase production of an auto part, the factory manager decides to play music in the manufacturing area. Eight workers are selected, and the number of items each produced for a specific day is recorded. After one week of music, the same workers are monitored again. The data are given in "music" worksheet. At α = 0.05, can the manager conclude that the music has increased production?

Exercise 6) The profits of a random sample of banks during 1990 and 1991 were observed. Does the data suggest, at the 10% significance level, that the mean profits of banks in 1990 and 1991 differ?

Part B -

Exercise 1) North American automobile manufacturers have become more concerned with quality because of foreign competition. One aspect of quality is the cost of repairing damage caused by accidents. A manufacturer is considering several new types of bumpers. In order to test how well they react to low-speed collisions, 40 bumpers of each of four different types were installed on midsize cars, which were then driven into a wall at 5 miles per hour. The cost of repairing the damage in each case was assessed. The relevant data are stored in Bumpers worksheet.

a) Is there sufficient evidence to infer that the bumpers differ in their reactions to low-speed collisions?

b) If differences exist, use Tukey's method to determine which bumpers differ.

Exercise 2) A consumer agency investigated the premiums charged by four auto insurance companies. The agency randomly selected five drivers insured by each company who had similar driving records, autos, and insurance coverage. The following table gives the monthly premiums paid by the 20 drivers. Can you conclude that the average auto insurance premiums paid per month by all such drivers are the same for all four companies? Use α = 0.05.

Company A	Company B	Company C	Company D
$65	$48	$57	$62
73	69	61	53
54	88	89	45
43	75	77	51
70	72	69	44

Exercise 3) Part of an ANOVA table involving 8 groups for a study is shown below.

Source	DF	SS	MS	F	P-value
Treatment		126
Error		240
Total	67

a) Complete all the missing values in the above table and fill in the blanks.

b) Use α = 0.01 to determine if there is any significant difference among the means of the eight groups.

Exercise 4) Manufacturers of luxury cars are very much interested in knowing the age distribution of their customers because then they can change these models to attract younger buyers without losing the older customers who have traditionally favored such cars. The "Drivers" worksheet gives the ages of 7, 8 and 9 randomly selected primary drivers of these three makes of cars. At the 5% level of significance, can you conclude that the average age of drivers for each of these three makes of cars is the same?

Attachment:- Assignment File.rar