Lizzy: Out of the 80 students who took the biology exam, only 2/5 of them managed to score 100%. If a score below 80% qualified as failing, and 50 percent of the remaining students who didn't score 100% managed to score over 80%, calculate the number of students who failed the exam..
Me: Hmmm, let me think. I think this is the detailed solution:
The number of students who scored 100% is 2 / 5 * 80 = 32. Out of the 80 students, 80 - 32 = 48 did not score 100%. If 50% of the students who did not score 100% managed to score over 80%, then 50 / 100 * 48 = 24 students scored over 80%. The number of students who failed is 48 - 24 = 24. Final answer: 24.