# Test a Hypothesis and Confidence Interval

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Case Analysis: Riverside Chamber of Commerce

ABC Corporation of California publishes a variety of statistics, including the number of individuals who got a new job during the past 12 months and the mean length of time the individuals have been on the job. The Statistical Analysis Department of ASBC Corporation reported that the mean length of time of newly employed individuals in California was 17.00 weeks.

A local Chamber of Commerce for the City of Riverside has commissioned a study on the status of employment in the Riverside area. A sample of 16 employed residents of Riverside included data on the age and the number of weeks on a job. A portion of the data collected in October 2001 is shown as follows:

Age Weeks Employed Age Weeks Employed

55 21 25 6

30 18 40 21

23 11 25 13

52 36 25 11

41 19 59 34

25 12 49 27

42 7 33 18

45 25 35 20

In a 1,050-1,750-word analysis, address the following:

a. Based on the above data, use descriptive statistics to summarize the data.

b. Develop a 99% confidence interval estimate of the mean age of newly hired employees.

c. Conduct a hypothesis test to individuals and determine whether the mean duration of employment in Riverside is greater than the California mean duration of 17.00 weeks. Use a .01 level of significance. What is your conclusion?

Ho= Mean duration of employment in Riverside is greater than California

Ha= Mean duration of employment in Riverside is not greater than California.

d. Is there a relationship between the age of a newly employed individual and the number of weeks of employment? Explain. (For this case analysis, just answer the above questions in your prepared paper.) Use file name: QNT531 W2 Riverside Chamber Analysis last name.doc (where you will substitute your last name accordingly.)

NOTE: Also, please look at the attached document. Thanks

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##### Solution Summary

The solution answers the questions in regard to summarizing the data, creating the confidence interval, and the hypothesis testing steps to determine if a relationship exists in the data.

###### Education

- BSc , Wuhan Univ. China
- MA, Shandong Univ.

###### Recent Feedback

- "Your solution, looks excellent. I recognize things from previous chapters. I have seen the standard deviation formula you used to get 5.154. I do understand the Central Limit Theorem needs the sample size (n) to be greater than 30, we have 100. I do understand the sample mean(s) of the population will follow a normal distribution, and that CLT states the sample mean of population is the population (mean), we have 143.74. But when and WHY do we use the standard deviation formula where you got 5.154. WHEN & Why use standard deviation of the sample mean. I don't understand, why don't we simply use the "100" I understand that standard deviation is the square root of variance. I do understand that the variance is the square of the differences of each sample data value minus the mean. But somehow, why not use 100, why use standard deviation of sample mean? Please help explain."
- "excellent work"
- "Thank you so much for all of your help!!! I will be posting another assignment. Please let me know (once posted), if the credits I'm offering is enough or you ! Thanks again!"
- "Thank you"
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