A. A researcher was interested in comparing the GPAs of studentsat two different colleges. Independent simple random samples of 8students from college A and 13 students from college B yielded thefollowing results. The mean GPA for college A was x1 = 3.11, with astandard deviation s1 = 0.44. The GPA for college B was 2 = 3.44,with a standard deviation s2 = 0.55. Determine a 95% confidenceinterval for the difference, µ1-µ2 between the mean GPA of collegeA students and the mean GPA of college B students. (Assume collegea and B have the same population standard deviations)

B. A manufacturing process produces bags of cookies. Thedistribution of content weights of these bags is Normal with mean15.0 oz and standard deviation 6.0 oz. We will randomly select asample of 900 bags of cookies and weigh the contents of each bagselected, is the mean of such sample

a) The mean of is x

b) The standard deviation of x is

c) The distribution of x is

d) Does the distribution of depend on the assumption that theweight (in oz) of these bags is normally distributed and why?

C.Last year, the mean annual salary for adults in one town was$35,000. A researcher wants to perform a hypothesis test todetermine whether the mean annual salary for adults in this townhas changed this year. The mean annual salary for a random sampleof 16 adults from the town was 33000. Assume population standarddeviation σ =12000. Use a significance level of α=0.05

D. A special diet is intended to reduce the cholesterol ofpatients at risk of heart disease. After six months on the diet, anSRS of 64 patients at risk for heart disease had an averagecholesterol of x= 192, with standard deviation s = 24. The 95%confidence interval for the average cholesterol of patients at riskfor heart disease who have been on the diet for 6 months is