Statistics Practitioner

Question

      1.  Calculate the following:

a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10.

b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence  

     2. a) From the information given here, determine the 95% confidence interval estimate of   the population mean. Xbar = 100 s = 20 n = 25

b) Repeat part (a) with xbar = 200.

c) Repeat part (a) with xbar = 500

d) Describe what happens to the width of the confidence interval estimate when the sample mean increases.   

Question

A statistics practitioner randomly sampled 100 observations from a population whose standard deviation is 5 and found that is 10. Estimate the population mean with 90% confidence.     

 B. Repeat Part A with sample size of 25.     

 C. Repeat Part A with a sample size of 10.      

D. Describe what happens to   the confidence interval estimate when the sample size decreases.