The following table shows the number of licensed U.S. drivers by age and by
sex (www.dot.gov):
$$
\begin{array}{l|rr|r}
\text { Age } & \begin{array}{c}
\text { Male Drivers } \\
\text { (number) }
\end{array} & \begin{array}{c}
\text { Female Drivers } \\
\text { (number) }
\end{array} & \text { Total } \\
\hline 19 \text { and under } & 4,777,694 & 4,553,946 & \mathbf{9 , 3 3 1 , 6
4 0} \\
20-24 & 8,611,161 & 8,398,879 & \mathbf{1 7 , 0 1 0 , 0 4 0} \\
25-29 & 8,879,476 & 8,666,701 & \mathbf{1 7 , 5 4 6 , 1 7 7} \\
30-34 & 9,262,713 & 8,997,662 & \mathbf{1 8 , 2 6 0 , 3 7 5} \\
35-39 & 9,848,050 & 9,576,301 & \mathbf{1 9 , 4 2 4 , 3 5 1} \\
40-44 & 10,617,456 & 10,484,149 & \mathbf{2 1 , 1 0 1 , 6 0 5} \\
45-49 & 10,492,876 & 10,482,479 & \mathbf{2 0 , 9 7 5 , 3 5 5} \\
50-54 & 9,420,619 & 9,475,882 & \mathbf{1 8 , 8 9 6 , 5 0 1} \\
55-59 & 8,218,264 & 8,265,775 & \mathbf{1 6 , 4 8 4 , 0 3 9} \\
60-64 & 6,103,732 & 6,147,569 & \mathbf{1 2 , 2 5 1 , 3 6 1} \\
65-69 & 4,571,157 & 4,643,913 & \mathbf{9 , 2 1 5 , 0 7 0} \\
70-74 & 3,617,908 & 3,761,039 & \mathbf{7 , 3 7 8 , 9 4 7} \\
75-79 & 2,890,155 & 3,192,408 & \mathbf{6 , 0 8 2 , 5 6 3} \\
80-84 & 1,907,743 & 2,222,412 & \mathbf{4 , 1 3 0 , 1 5 5} \\
85 \text { and over } & 1,170,817 & 1,406,271 & \mathbf{2 , 5 7 7 , 0 8 8} \\
\hline \text { Total } & \mathbf{1 0 0 , 3 8 9 , 8 8 1} & \mathbf{1 0 0 , 2 7
5 , 3 8 6} & \mathbf{2 0 0 , 6 6 5 , 2 6 7}
\end{array}
$$
a) What percent of total drivers are under 20 ?
b) What percent of total drivers are male?
c) Write a few sentences comparing the number of male and female licensed
drivers in each age group.
d) Do a driver's age and sex appear to be independent? Explain?