Question

In Kendra’s class, 40 percent of the students earned an A on the math test. Twenty students earned an A. Kendra needs to find out how many students are in her class. Kendra’s work is shown below.

StartFraction part Over whole EndFraction = StartFraction 40 divided by 2 Over 100 times 2 EndFraction = StartFraction 20 Over 200 EndFraction

What mistake did Kendra make?
Kendra should have multiplied by 4 in both the numerator and the denominator.
Kendra should have divided by 2 instead of multiplying by 2 in the denominator.
Kendra should have added 40 and 20.
Kendra should have the part to whole equation written as StartFraction 100 Over 40 EndFraction.

Answer 1

Kendra should have used a proportion to find the total number of students. By cross-multiplying 40/100 = 20/x, and solving for x, we find out there are 50 students in her class.

Step-by-step explanation:

Kendra made a mistake in her calculation to find out the total number of students in her class based on the percentage that earned an A on the math test.

To find the total number of students in her class, she should set up a proportion where 40 is to 100 as the number of students who got an A (20) is to the total number of students in the class (let's call this total number x). The correct proportion looks like 40/100 = 20/x.

To solve for x, we can cross-multiply to get 40x = 2000. Dividing both sides of the equation by 40 will give us x = 50. Therefore, there are 50 students in Kendra's class.