Question

If the white flags are flown on poles 2 and 3, which of the following must be true?

• A. \( \text{A green flag is flown on pole 4.} \)
• B. \( \text{A green flag is flown on pole 6.} \)
• C. \( \text{A green flag is flown on pole 7.} \)
• D. \( \text{A yellow flag is flown on pole 1.} \)
• E. \( \text{A yellow flag is flown on pole 7.} \)

Hint:

Ensure green non-adjacency and pole 3 restriction.

Answer 1

The Correct Option is A

Step 1: White flags on 2 and 3, leaving 3 green and 2 yellow for poles 1, 4, 5, 6, 7.
Step 2: No green on 3, and green flags cannot be adjacent, so 4 must be green to separate from potential greens on 1 or 5.
Step 3: Yellow cannot be on 5, so 5 must be green or part of remaining placement, but 4 green ensures non-adjacency.
Step 4: Any configuration (e.g., 1Y, 4G, 5G, 6Y, 7G) requires 4G to avoid adjacent greens, making (A) must be true.