The following data have been collected by an accountant who is performing an audit of paper products at a large office supply company. The dependent variable, y, is the time (in minutes) the accountant takes to count the units.

The independent variable, x, is the number of units on the computer inventory record.

y 23.1 100.5 242.9 56.4 178.7 10.5 94.2 200.4 44.2 128.7 180.5 x 24 120 228 56 190 13 85 190 32 120 230

a. Develop a scatter plot for these data.

b. Determine the regression equation representing the data. Is the model significant? Test using a significance level of 0.10 and the p-value approach.

c. Develop a 90% confidence interval estimate for the true regression slope and interpret this interval estimate. Based on this interval, could you conclude the accountant takes an additional minute to count each additional unit?