The table below shows the soft drink preferences of people in three age groups. \begin{tabular}{l|lcc} & cola & root beer & lemon-lime \\ \hline under 21 years of age & 40 & 25 & 20 \\ between 21 and 40 & 35 & 20 & 30 \\ over 40 years of age & 20 & 30 & 35 \end{tabular} If one of the 255 subjects is randomly selected, find the probability that the person is over 40 years of age. A. $\frac{2}{5}$ B. $\frac{3}{5}$ C. $\frac{1}{2}$ D. $\frac{1}{3}$

Step 1 ：First, we need to find the total number of people over 40. Looking at the table, we can see that there are 20 people who prefer cola, 30 who prefer root beer, and 35 who prefer lemon-lime. So, the total number of people over 40 is 20 + 30 + 35, which equals 85.

Step 2 ：Next, we need to find the total number of people. The question tells us that there are 255 subjects in total.

Step 3 ：Finally, we can calculate the probability by dividing the number of people over 40 by the total number of people. The probability is \(\frac{85}{255}\), which simplifies to \(\frac{1}{3}\).

Step 4 ：Final Answer: The probability that a randomly selected person is over 40 years of age is \(\boxed{\frac{1}{3}}\).