Using: sigma known or sigma unknown

1. What is the Z-value for 95% level of confidence?

2. What is the Z-value for 99% level of confidence?

3. If X = 85, = 8, and n = 64, construct a 95% confidence interval estimate for the population

mean, . Explain. (CIE Sigma known.xls)

4. When the population standard deviation is unknown, how can the confidence interval be

estimated?

5. What is the critical value from the t-distribution for a 95% level of confidence? (Use the Question 3 as the source for the data).

6. If X = 75 S = 24, and n = 36, assuming that the population is normally distributed, construct a 95%

confidence interval estimate for the population mean, . Explain. (CIE Sigma Unknown.xls)

Sigma Known:

Estimate for the Mean Paper Length Data Population Standard Deviation 0.02 Sample Mean 10.998 Sample Size 100 Confidence Level Intermediate Calculations Standard Error of the Mean 0.002 z Value -1.9800 Interval Half Width 0.0039 Confidence Interval Interval Lower Limit 10.9941 Interval Upper Limit 11.0019Estimate for the Mean Paper Length Data Population Star 0.02 Sample Mean 10.998 Sample Size 100 Confidence Lev Intermediate Calculations Standard Error 0.002 BnjBAZ -1.9600 M JIBH JBAJBIUI 0.0039 Confidence Interval Interval Lower 10.9941 Interval Upper 11.0019Estimate for the Mean Sales Invoice Amount Data Sample Standard Deviation 28 95 Sample Mean 110.27 Sample Size 100 Confidence Level Intermediate Calculations Standard Error of the Mean 2.8950 Degrees of Freedom 99 cValue 1.9842 Interval Half width 5.7449 Confidence Interval Interval Lower Limit 104 53 Interval Upper Limit 110.01Estimate for the Mean Sales Invoice Amount Data Sample Standar 28.95 Sample Mean 110.27 Sample Size 100 Confidence Lev intermediate Calculations Standard Error Degrees of Fre f Value 1.9542 Interval Half wi 5.7443 Confidence Interval Interval Lower 104.53 Jadon |BAJEQUI 116.01