🎴 Flashcard Mode
Math Puzzles and Number Series
Card1 / 20
Mastered0
Review0
QuestionClick to flip
In an examination, there are three subjects A, B and C. A student has to pass in each subject. 20% students failed in A, 22% students failed in B and 16% failed in C. The total number of students passing the whole examination lies between
AnswerClick to flip back
A
42% and 78%
💡 Explanation:
Using set theory, maximum students passing all subjects occurs when failures don't overlap: 100-20=80% pass A, 100-22=78% pass B, 100-16=84% pass C, so max pass all = 78%. Minimum occurs when failures maximally overlap: minimum pass = 100-(20+22+16)=42%. This gives range 42% to 78%. Option C's lower bound of 58% is too high - it incorrectly assumes no overlap.