Reference no: EM132236628

Business Statistics Assignment -

Use Excel Phstat for problems. Work with hypothesis testing and testing differences in mean values across multiple groups.

Problem 1 - An insurance company has the business objective of reducing the amount of time it takes to approve applications for life insurance. The approval process consists of underwriting, which includes a review of the application, a medical information bureau check, possible requests for additional medical information and medical exams, and a policy compilation stage in which the policy pages are generated and sent for delivery. The ability to deliver approved policies to customers in a timely manner is critical to the profitability of this service. During a period of one month, you collect a random sample of 27 approved policies and the total processing time, in days, stored in Insurance, are:

73	19	16	64	28	28	31	90	60	56	31	56	22	18	45	48
17	17	17	91	92	63	50	51	69	16	17

a. In the past, the mean processing time was 45 days. At the 0.05 level of significance, is there evidence that the mean processing time has changed from 45 days?

b. What assumption about the population distribution is needed in order to conduct the t test in (a)?

c. Construct a box-plot or a normal probability plot to evaluate the assumption made in (b).

d. Do you think that the assumption needed in order to conduct the t test in (a) is valid? Explain.

Problem 2 - One of the major measures of the quality of service provided by any organization is the speed with which it responds to tower complaints. A large family-held department store selling furniture and flooring, including carpet, had undergone a major expansion in the past several years. In particular, the flooring department had expanded from 2 installation crews to an installation supervisor, a measurer, and 15 installation crews. The store had the business objective of improving its response to complaints. The variable of interest was defined as the number of days between when the complaint was made and when it was resolved. Data were collected from 50 complaints that were made in the past year. These data, stored in Furniture, are:

54	5	35	137	31	27	152	2	123	81	74	27
11	19	126	110	110	29	61	35	94	31	26	5
12	4	165	32	29	28	29	26	25	1	14	13
13	10	5	27	4	52	30	22	36	26	20	23
33	68

a. The installation supervisor claims that the mean number of days between the receipt of a complaint and the resolution of the complaint is 20 days. At the 0.05 level of significance, is there evidence that the claim is not true (i.e., the mean number of days is different from 20)?

b. What assumption about the population distribution is needed in order to conduct the t test in (a)?

c. Construct a boxplot or a normal probability plot to evaluate the assumption made in (b).

d. Do you think that the assumption needed in order to conduct the t test in (a) is valid? Explain.

Problem 3 - A problem with a phone line that prevents a customer from receiving or making calls is upsetting to both the customer and the telecommunications company. The file Phone contains samples of 20 problems reported to two different offices of a telecommunications company and the time to clear these problems (in minutes) from the customers' lines:

Central Office I Time to Clear Problems (minutes)

1.48	1.75	0.78	2.85	0.52	1.60	4.15	3.97	1.48	3.10
1.02	0.53	0.93	1.60	0.80	1.05	6.32	3.93	5.45	0.97

Central Office H Time to Clear Problems (minutes)

7.55	3.75	0.10	1.10	0.60	0.52	3.30	2.10	0.58	4.02
3.75	0.65	1.92	0.60	1.53	4.23	0.08	1.48	1.65	0.72

a. Assuming that the population variances from both offices are equal, is there evidence of a difference in the mean waiting time between the two offices? (Use α = 0.05.)

b. Find the p-value in (a) and interpret its meaning.

c. What other assumption is necessary in (a)?

d. Assuming that the population variance from both offices are equal, construct and interpret a 95% confidence interval estimate of the difference between the population means in the two offices.

Attachment:- Assignment Files.rar