Skip to main content
OlympiadHQ

Browse · harp

Print

smc

counting and probability senior

Problem

At Typico High School, of the students like dancing, and the rest dislike it. Of those who like dancing, say that they like it, and the rest say that they dislike it. Of those who dislike dancing, say that they dislike it, and the rest say that they like it. What fraction of students who say they dislike dancing actually like it?
(A)
(B)
(C)
(D)
Solution
WLOG, let there be students. of them like dancing, and do not. Of those who like dancing, , or of them say they dislike dancing. Of those who dislike dancing, , or of them say they dislike it. Thus,
Final answer
D