SOLUTION: In a large class, 80 students took a test. When the test papers were rated, it was found that 10% of the students had A papers, 23% had B papers, 30% had C papers, 15% had D papers

Question 164874: In a large class, 80 students took a test. When the test papers were rated, it was found that 10% of the students had A papers, 23% had B papers, 30% had C papers, 15% had D papers, and the rest failed. How many students failed the test?
Answer by Mathtut(3670) (Show Source): You can put this solution on YOUR website!
well, we know that all the students(80) comprise 100%. so if we add all the percentages of each group together and subtract that from 100% that will give us the percentage of failed students. 10+23+30+15=78% 100-78=22%. So then 22% of the students failed. In terms of numbers of students that would be 80 times 22%(or 22/100 or .22) which equals 17.6. Since there cant be 6/10 of a person... lets round up and we get 18 students that failed.
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