First, let’s convert the ratio to a fraction. Because a ratio is the comparison of two parts and a fraction is a ratio of parts to whole, we can add the ratio together to get the total passing and failing grades.
7:5 ——> 7+5=12
Since 5 represents the number of failing grades, 5/12 grades are failing grades.
Now, we need to find the number of failing students given a total of 36 students. We can create a proportion and use “x” for the number of failing students.
5/12=x/36
Cross multiply to solve for x:
5•36=12•x
Simplify:
180=12x
Divide both sides by 12 to isolate x:
180/12=x
15=x
Apply the symmetric property:
x=15
This means that 15 students are failing the class. Let’s make sure these two fractions are indeed equivalent by plugging x=-5 back into the equation:
5/12=15/36
.416=.416
Because the quotients are equal, the fractions are proportional.
So, your answer is 15/36 students are failing