Official Solution: Out of 180 gym members, is the number of members who attend yoga sessions greater than the number who attend strength training sessions? (1) Every member who attends yoga sessions also attends at least one other type of session.
This tells us that no one attends only yoga, but it doesn’t specify
which other session is attended. So:
Suppose 10 members attend yoga, and all of them also attend cardio. Strength training has 5 members. Then yoga > strength, so the answer is Yes.
Suppose 10 members attend yoga, and all of them also attend cardio. Strength training has 50 members. Then yoga < strength, so the answer is No.
Not sufficient.
(2) Every member who attends yoga sessions also attends strength training sessions.
This means the entire yoga group is included in the strength training group. So yoga cannot be greater than strength, giving a definite No answer to the question. Sufficient.
Answer: B