65. The article “Chronological Trend in Blood Lead Levels”

(N. Engl. J. Med., 1983: 1373–1377) gives the following data on y
average blood lead level of white children age 6 months to 5 years and x
amount of lead used in gasoline production (in 1000 tons) for ten 6-month periods:

a. Construct separate normal probability plots for x and y.

Do you think it is reasonable to assume that the (x, y)

pairs are from a bivariate normal population?

b. Does the data provide sufficient evidence to conclude that there is a linear relationship between blood lead level and the amount of lead used in gasoline production? Use 
.01.