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Calculating Mean and Standard Deviation: New Jobs Example

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The Department of Economic and Community Development (DECD) reported that in 2008 that average number of new jobs created per county was 450. The department also provided that following information regarding a sample of five counties in 2009.

Bradley 410
Rhea 450
Marion 407
Grundy 428
Sequatchie 400

a. Calculate the sample mean and sample standard deviation for new jobs created per county in year 2009.

Sample mean = (410+450+407+428+400)/ 5= 419

Sample Standard deviation = [(410-419)2 + (450-419)2+ (407-419)2+ (428-419)2+ (400-419)2] / 5-1= 407

b. If we want to determine whether there has been a significant decrease in the average number of jobs created, what are the null and alternative hypotheses you will test?

Ho: mu > = 450
Ha: mu < 450

c. At significance level of a= 0.05, calculate your test statistic and compare it with the critical value, what is your conclusion?

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Solution Summary

Provides steps necessary to determine mean and standard deviation.

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