The ages and grades of some of the 17 girls on a club soccer team are shown in the table.

\begin{tabular}{|c|c|c|}
\hline
& 15 years old & 16 years old \\
\hline
9th grade & 2 & 0 \\
\hline
10th grade & 5 & 10 \\
\hline
\end{tabular}

Which two-way frequency table correctly shows the marginal frequencies?

A.
\begin{tabular}{|c|c|c|c|}
\hline
& \begin{tabular}{c} 15 years \\ old \end{tabular} & \begin{tabular}{c} 16 years \\ old \end{tabular} & Total \\
\hline
9th grade & 2 & 0 & 2 \\
\hline
10th grade & 5 & 10 & 15 \\
\hline
Total & 7 & 10 & 17 \\
\hline
\end{tabular}

B.
\begin{tabular}{|c|c|c|c|}
\hline
& \begin{tabular}{c} 15 years \\ old \end{tabular} & \begin{tabular}{c} 16 years \\ old \end{tabular} & Total \\
\hline
9th grade & 2 & 0 & 2 \\
\hline
10th grade & 15 & 10 & 25 \\
\hline
Total & 17 & 10 & 27 \\
\hline
\end{tabular}



Answer :

To determine the correct two-way frequency table with the marginal frequencies, we will go through the given data step by step.

Given:
- For 9th grade: 2 girls are 15 years old, 0 girls are 16 years old.
- For 10th grade: 10 girls are 16 years old.

We need to fill in the missing value for the 10th grade, 15 years old and calculate the marginal frequencies (totals).

### Step-by-step Calculation:

Step 1: Fill in the missing value for 10th grade, 15 years old.
- Given that the total number of girls is 17 and the sum of known values is [tex]\(2\)[/tex] (from 9th grade, 15 years old) + [tex]\(0\)[/tex] (from 9th grade, 16 years old) + [tex]\(10\)[/tex] (from 10th grade, 16 years old) = [tex]\(12\)[/tex].
- Therefore, the number of 15-year-old girls in 10th grade = [tex]\(17 - 12 = 5\)[/tex].

Now we have:
- 9th grade: 15 years old = 2, 16 years old = 0.
- 10th grade: 15 years old = 5, 16 years old = 10.

Step 2: Calculate the row and column totals (marginal frequencies).
- Row totals (grades):
- [tex]\(9\)[/tex]th grade total = [tex]\(2\)[/tex] (15 years old) + [tex]\(0\)[/tex] (16 years old) = [tex]\(2\)[/tex].
- [tex]\(10\)[/tex]th grade total = [tex]\(5\)[/tex] (15 years old) + [tex]\(10\)[/tex] (16 years old) = [tex]\(15\)[/tex].

- Column totals (ages):
- Total 15 years old = [tex]\(2\)[/tex] (9th grade) + [tex]\(5\)[/tex] (10th grade) = [tex]\(7\)[/tex].
- Total 16 years old = [tex]\(0\)[/tex] (9th grade) + [tex]\(10\)[/tex] (10th grade) = [tex]\(10\)[/tex].

- Grand total = [tex]\(9\)[/tex]th grade total + [tex]\(10\)[/tex]th grade total = [tex]\(2\)[/tex] + [tex]\(15\)[/tex] = [tex]\(17\)[/tex].

Step 3: Construct the two-way frequency table.
Given our calculations, the table should look like this:

[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & 15 \text{ years old} & 16 \text{ years old} & \text{Total} \\ \hline 9th grade & 2 & 0 & 2 \\ \hline 10th grade & 5 & 10 & 15 \\ \hline \text{Total} & 7 & 10 & 17 \\ \hline \end{tabular} \][/tex]

### Conclusion:
The correct two-way frequency table is Option A:

[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & 15 \text{ years old} & 16 \text{ years old} & \text{Total} \\ \hline 9th grade & 2 & 0 & 2 \\ \hline 10th grade & 5 & 10 & 15 \\ \hline \text{Total} & 7 & 10 & 17 \\ \hline \end{tabular} \][/tex]