Question

# Is there a relationship between Facebook use and age among college students? The following two-way table displays data for the 219 students who respon

Two-way tables

Is there a relationship between Facebook use and age among college students? The following two-way table displays data for the 219 students who responded to the survey.$$\begin{array}{ccc} \ \text{Facebook user?} & {\begin{array}{l|c|c|c} & \begin{array}{c} \text { Younger } \\ (18-22) \end{array} & \begin{array}{c} \text { Age Middle } \ (23-27) \end{array} & \begin{array}{c} \text { Older } \\ (28 \text { and up)} \end{array} \\ \hline \text { Yes } & 78 & 49 & 21 \\ \hline \text { No } & 4 & 21 & 46 \end{array}} \\ \end{array}$$ What percent of the students in the sample were aged 28 or older?

2021-05-20
Let us first determine the row/column totals of the given table, which is the sum of all counts in the row/column:
Yonger Middle Older Row total
Yes 78 49 21 78+49+21=148
No 4 21 46 4+21+46=71
Column total 78+4=82 49+21=70 21+46=67 148+71=219
We the note that the table contains 219 students in total (which is given in the bottom right corner of the above table), while 21 of the 219 students are older and Facebook users (which is given in the row ”Yes” and in the column *Older” of the above table).
$$\displaystyle\frac{{67}}{{219}}\sim{0.3059}={30.59}\%$$
Thus 9.589% of the students who responded were older Facebook users.