10.22 [EX10-022] In evaluating different measuring instruments, one must first determine whether there is a systematic difference between the instruments. Lenses from several different powers were measured once each by two different instruments. The measurement differences (Instrument A  Instrument B) were recorded. The measurement units have been coded for proprietary reasons.

4 5 2 3 7 10 11 1 3 7 5 3 4

5 7 4 1 18 0 17 12 9 4 17 2 Does there appear to be a systematic difference between the two instruments?

a. Describe the data using a histogram and one other graph.

b. Find the mean and the standard deviation.

c. Are the assumptions required for making inferences satisfied? Explain.

d. Using a 95% confidence interval, estimate the population mean of the differences.

e. Is there any evidence of a difference? Explain.