Find the indicated probability. Express your answer as a simplified fraction unless otherwise noted.
-The table below shows the soft drinks preferences of people in three age groups. $$\begin{array} { r | c c c }
& \text { cola } & \text { root beer } & \text { lemon-lime } \
\hline \text { under 21 years of age } & 40 & 25 & 20 \
\text { between 21 and 40 } & 35 & 20 & 30 \
\text { over 40 years of age } & 20 & 30 & 35
\end{array}$$ If one of the 255 subjects is randomly selected, find the probability that the person drinks root beer given that they are over 40.
A) $\frac { 2 } { 17 }$
B) $\frac { 2 } { 5 }$
C) $\frac { 6 } { 17 }$
D) None of the above is correct.

Question

Find the indicated probability. Express your answer as a simplified fraction unless otherwise noted.
-The table below shows the soft drinks preferences of people in three age groups. $$\begin{array} { r | c c c } 
& \text { cola } & \text { root beer } & \text { lemon-lime } \
\hline \text { under 21 years of age } & 40 & 25 & 20 \
\text { between 21 and 40 } & 35 & 20 & 30 \
\text { over 40 years of age } & 20 & 30 & 35
\end{array}$$ If one of the 255 subjects is randomly selected, find the probability that the person drinks root beer given that they are over 40. 
A) $\frac { 2 } { 17 }$
B) $\frac { 2 } { 5 }$
C) $\frac { 6 } { 17 }$
D) None of the above is correct.

Quizplus · Accepted Answer

The probability of a person being over 40 is $\frac{20+30+35}{255} = \frac{85}{255} = \frac{1}{3}$. 
Out of the 85 people over 40, 30 of them prefer root beer. 
Therefore, the probability of a person being over 40 and preferring root beer is $\frac{30}{255}=\frac{2}{17}$. 
So the answer is A: $\frac{2}{17}$.

Find the Indicated Probability If One of the 255 Subjects Is Randomly Selected, Find