Final answer:
The student has made 70 percent of the total number of cards, which was calculated by setting up equivalent fractions (196/280 = percentage/100) and solving for the percentage by cross-multiplying and dividing.
Step-by-step explanation:
To calculate the percentage of cards made by the student, we can use the concept of equivalent fractions where one of the fractions has a denominator of 100. The fraction with the cards made (196) as the numerator and a total number of students (280) as the denominator, is equivalent to a fraction with a denominator of 100 that will represent the percentage we are looking for.
The equivalent fractions would be set up as follows:
(cards made / total number of students) = (percentage / 100)
By plugging in the numbers:
(196 / 280) = (percentage / 100)
By cross-multiplying and solving for the percentage, we get:
196 * 100 = percentage * 280
19600 = percentage * 280
Now, divide both sides by 280 to solve for the percentage:
percentage = 19600 / 280
percentage = 70
Therefore, the student has made 70 percent of the total number of cards.