Question

1. An article from an Environmental Engineering journal reported the results of a study on the occurrence
of sodium and chloride on the surface of water currents in Rhode Island. The following data presents
the concentration of chloride designated ? (in milligrams per liter) and the taxiway area in the basin
as ? (in percentage).
? 4.4 6.6 9.7 10.6 10.8 10.9
? 0.19 0.15 0.57 0.70 0.67 0.63
? 11.8 12.1 14.3 14.7 15.0 17.3
? 0.47 0.70 0.60 0.78 0.81 0.78
? 19.2 23.1 27.4 27.7 31.8 39.5
? 0.69 1.30 1.05 1.06 1.74 1.62
a) Draw a scatter diagram of the data. Does a simple linear model look appropriate?
b) Adjust the simple linear regression using the least squares method. Find the
estimate of σ
two
.
c) Estimate the average concentration of chloride for the basin that has 1% taxi area.
d) Find the adjusted value corresponding to ? = 0.47 and the associated residual.

2. Consider the data from exercise # 1 where ? is equal to the concentration of chloride on the surfaces of
current and ? is the taxi area.
a) Test the hypothesis Ho: β1 = 0 versus H1: β1 ≠ 0 using the analysis of variance procedure
with α = 0.01.
b) Find the p-value for the test of part a.
c) Estimate the standard errors for β
1 and β
0

Answer 1