Ms. Burger has graded 45 tests. This represents 60% of her 3 math classes. How many math students does Ms. Burger teach?

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Ms. Burger has graded 45 tests. This represents 60% of her 3 math classes. How many math students does Ms. Burger teach?

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Answer 1 · 2016-12-26T09:03:42

$75$ students.

We assume that the $45$ tests graded only account for $60%$ of her students (i.e. only $60%$ of them on average showed up to class on test day!).

So, we have the equation:

$0.60s = 45$

where $s$ is the total number of students, so that " $0.60s$ " conveys the phrase, "60% of [the] 3 math classes" and sets that equal to the number of tests graded, $45$ .

Note that $60%$ is also representable in decimal form as $0.60$ , since percent means "out of 100".

That means the total number of students (not distinguishing between the number of students per class) is:

$color(blue)(s) = 45/0.60 = color(blue)(75)$
(we divided both sides by $0.60$ )

NOTE: A common mistake is to write:

$s = 0.60xx45$ ,

which is backwards. It would say that there were more tests given out than students who took the test. Make sure your answer makes physical sense.

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Ms. Burger has graded 45 tests. This represents 60% of her 3 math classes. How many math students does Ms. Burger teach?

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