a group of 120 seventh - and eighth - grade students were asked whether they participate in sports or in non…

Explanation:

Step1: Evaluate the first statement.

The first statement is "Twenty-nine seventh-grade students chose a sports activity." From the table, the number of seventh-grade students who chose a sports activity is found at the intersection of the "Seventh Grade" row and the "Sports" column, which is 39. Since $39 \neq 29$, the first statement is incorrect.

Step2: Evaluate the second statement.

The second statement is "Twenty-eight eighth-grade students chose a sports activity." From the table, the number of eighth-grade students who chose a sports activity is found at the intersection of the "Eighth Grade" row and the "Sports" column, which is 29. Since $29 \neq 28$, the second statement is incorrect.

Step3: Evaluate the third statement.

The third statement is "Twenty-four seventh-grade students chose a non-sports activity." From the table, the number of seventh-grade students who chose a non-sports activity is found at the intersection of the "Seventh Grade" row and the "Non-Sports" column, which is 24. Since $24 = 24$, the third statement is correct.

Step4: Evaluate the fourth statement.

The fourth statement is "Thirty-nine eighth-grade students chose a non-sports activity." From the table, the number of eighth-grade students who chose a non-sports activity is found at the intersection of the "Eighth Grade" row and the "Non-Sports" column, which is 28. Since $28 \neq 39$, the fourth statement is incorrect.

Answer:

Twenty-four seventh-grade students chose a non-sports activity.