Question: (6 pt dataset in Excel file) Rex Boggs of Australia weighs his bar of soap each morning before showering. The weight decreases as the soap is used, and the measurements appear below (in grams).

Day 01 02 05 06 07 08 09 10 12 13 16 18 19 20 21

Weight 124 121 103 96 90 84 78 71 58 50 27 16 12 8 6

a. You have data for days of use and soap weight — which is the explanatory (X) variable, and which the response M?

b. Make a scatterplot of how the soap weight depends on days of use. Put the regression line and R² values on the plot.

c. Mr. Boggs did not measure the weight of the soap on Day 4. Use the regression line to predict the weight of the soap.

d. Do you believe the predicted soap weight on Day 4 will be an accurate estimate of the true weight of the soap that day?

e. Use the regression equation to predict the weight of the soap after 30 days.

f.. Does the result you calculated in Part E make sense?