In tests designed to measure the effect of a certain additive on the drying time of paint, the following data were obtained.
Concentration
of Additive (%) Drying Time (h)
4.0 8.7
4.2 8.8
4.4 8.3
4.6 8.7
4.8 8.1
5.0 8.0
5.2 8.1
5.4 7.7
5.6 7.5
5.8 7.2
a. Construct a scatterplot of drying time (y) versus
a. Let A = βˆ0 + βˆ1C be the equation of the additive concentration (x).
b. Compute the least-squares line for predicting drying time from additive concentration.
c. Compute the fitted value and the residual for each point.
d. If the concentration of the additive is increased by 0.1%, by how much would you predict the drying time to increase or decrease?
e. Predict the drying time for a concentration of 4.4%.
f. For what concentration would you predict a drying time of 8.2 hours?