Ms. Quarles gave a math unit test to each of her four classes. Each class has the same number of students. Ms. Quarles grades 25% of the tests, which is 30 papers. How many students does she have in each class?
There are different ways to approach this problem, but one possible method is:
Let n be the number of students in each class. Then the total number of tests graded by Ms. Quarles is 4n (since there are four classes). According to the problem, 25% of the tests graded is 30 papers, which means:
0.25 x 4n = 30
Multiplying both sides by 4 and then dividing by 0.25, we get:
4n = 120
n = 30
Therefore, Ms. Quarles has 30 students in each class.