Question

How many persons attended the meeting?
I. Each registered person can take two persons with him/her.
II. There were totally 180 registrations for the meeting.

• A. If the statement I alone is sufficient to answer the question.
• B. If the statement II alone is sufficient to answer the question.
• C. If the statements I and II together are sufficient to answer the question but neither statement alone is sufficient.
• D. If the statements I and II together are not sufficient to answer the question and additional data is required.

Hint:

When given conditions with multipliers or groups, express the total number in terms of the variables and solve accordingly.

Answer 1

The Correct Option is D

Let the number of registered persons be \( x \). According to the problem, each registered person can take 2 persons with him/her, meaning the total number of persons who attended the meeting is: \[ \text{Total persons} = x + 2x = 3x \] From condition II, the total number of registrations is 180. Since each registration represents one person, we have: \[ x = 180 \] Thus, the total number of persons who attended the meeting is: \[ 3x = 3 \times 180 = 540 \] Therefore, the correct answer is \( \boxed{540} \). Thus, the correct answer is \( \boxed{4} \).