List of top Quantitative Ability and Data Interpretation Questions on Set Theory

In a school where there was a compulsion to learn at least one foreign language from the choices given, namely German, French and Spanish: 28 students took French, 30 took German, and 32 took Spanish. 6 students learnt French and German, 8 students learnt German and Spanish, and 10 students learnt French and Spanish. 54 students learnt only one foreign language, while 20 students learnt only German. Find the number of students in the school.
In a class, 52% of the students failed in English, 40% failed in Mathematics, and 20% failed in both the subjects. What percent of the students passed in both the subjects?