THE CORRECT ANSWER IS (C). TO ANSWER THE QUESTION, YOU NEED TO KNOW...
3. The correct answer is (C). To answer the question, you need to know (1) the total
number of dancers and (2) the number of dancers less than 25 years old. The question
provides the first number: 40. To find the second number, start with what the question
provides, and figure out what else you know. Keep going, and eventually you’ll arrive at
your destination. Of the whole group of 60, 24 are under 25 years old. (40 percent of 60
is 24.) 20 percent of the 20 singers, or 4 singers, are under 25 years old. Hence, the
remaining 20 people under 25 must be dancers. That’s the second number you needed to
answer the question. 20 is 50 percent of 40.