Chapter 9, Problem 2E

(a)

To determine

To explain is there a clear pattern or not and describe the trend.

Answer to Problem 2E

Yes, it is clear.

Explanation of Solution

The centers for disease control and Prevention track cigarette smoking in United States. The study was conducted on how the percentage of people who smoked changed over the years. The scatterplot is given on the percentage of smokers among men over the years. By looking at the scatterplot we can say that the percentage of smokers was at a steady decline until around $1990$ when there was a slight upturn again. So, we can conclude that the pattern is clear in the scatterplot.

(b)

To determine

To explain is the association strong or not.

Answer to Problem 2E

Yes, it is strong.

Explanation of Solution

The centers for disease control and Prevention track cigarette smoking in United States. The study was conducted on how the percentage of people who smoked changed over the years. The scatterplot is given on the percentage of smokers among men over the years. By looking at the scatterplot we can say that the percentage of smokers was at a steady decline until around $1990$ when there was a slight upturn again. So, we can conclude that the pattern is clear in the scatterplot. So, we can also say that there is a strong parabolic association in the scatterplot by looking at the pattern of the points.

(c)

To determine

To explain is a linear model appropriate or not.

Answer to Problem 2E

No, linear model is not appropriate.

Explanation of Solution

The centers for disease control and Prevention track cigarette smoking in United States. The study was conducted on how the percentage of people who smoked changed over the years. The scatterplot is given on the percentage of smokers among men over the years. By looking at the scatterplot we can say that the percentage of smokers was at a steady decline until around $1990$ when there was a slight upturn again. So, we can conclude that the shape of the scatterplot clearly shows a parabolic model would be much more appropriate. As the points shows the parabolic pattern in the scatterplot.