Final answer:
The marginal relative frequency for students who prefer swimming as their preferred type of exercise is 100%.
Step-by-step explanation:
To find the marginal relative frequency for students who prefer swimming as their preferred type of exercise, we need to look at the column totals in the table.
The column labeled 'Swimming' represents the total number of students who prefer swimming as their exercise type.
The column totals add up to 100%, so the marginal relative frequency for students who prefer swimming is also 100%.