A number of studies have shown lichens (certain plants composed of an alga and a fungus)...

A number of studies have shown lichens (certain plants composed of an alga and a fungus) to be excellent bioindicators of air pollution. The article “The Epiphytic Lichen Hypogymnia Physodes as a Biomonitor of Atmospheric Nitrogen and Sulphur Deposition in Norway” (Envir. Monitoring and Assessment, 1993: 27–47) gives the following data (read from a graph) on wet deposition (g /m²) and y = lichen (% dry weight):

The author used simple linear regression to analyze the data. Use the accompanying Minitab output to answer the following questions:

a. What are the least squares estimates of β₀ and β₁?

b. Predict lichen N for an deposition value of .5.

c. What is the estimate of σ ?

d. What is the value of total variation, and how much of it can be explained by the model relationship?