In an examination, 20% of the students failed in English, 20% failed in Mathematics and 17% failed in both. What percentage of students passed in both subjects?

💡 Solution & Explanation

Students who failed in at least one subject = failed in English + failed in Mathematics − failed in both (they were counted twice) = 20 + 20 − 17 = 23%. So the students who passed in both = 100 − 23 = 77%. Forgetting to subtract the 17% who failed in both gives 60%, which is too low.