Question

Mrs. Hubert gave a test to her chemistry class. 20% of the students failed. Of those students who failed, 10% are going to do retake. If she teaches 150 students, how many will do a retake?

Answer 1

3 students will retake the test

Explanation:

20% of 150 students is 30

(20÷100)×150=30 students

Now we need to find the 10% of the 30 students who failed.

(10÷100)×30=3 students

we can check this by Subtracting that 20% who failed from 100%(the total in class). So that will be 80%. Now that 80% is the number of students who passed.

And in order to find the number of students who passed we say:

(80÷100)×150= 120

all you need to do now is, subtract that 120 from 150, then find the 10% of the answer.