Questions 7-11

A worker will insert colored light bulbs into a billboard equipped with exactly three light sockets, which are labled lights 1, 2, and 3. The worker has three green bulbs, three purple bulbs, and three yellow bulbs. Seiection of bulbs for the sockets is governed by the following conditions:

Whenever light 1 is purple, light 2 must be yellow.

Whenever light 2 is purple, light 1 must be green.

Whenever light 3 is either purple or yellow, light 2 must be purple.

7. Which one of the following could be an accurate list of the colors of light bulbs selected for lights 1, 2 and 3, respectively?

　(A) green, green, yellow
　(B) purple, green, green
　(C) purple, purple, green
　(D) yellow, purple, green
　(E) yellow, yellow, yellow

8. If light 1 is yellow, then any of the following can be true, EXCEPT:

　(A) Light 2 is green.
　(B) Light 2 is purple
　(C) Light 3 is green
　(D) Light 3 is purple
　(E) Light 3 is yellow

9. There is exactly one possible color sequence of the three lights if which one of the following is true?

　(A) Light 1 is purple.
　(B) Light 2 is purple.
　(C) Light 2 is yellow
　(D) Light 3 is purple.
　(E) Light 3 is yellow
　
10. If no green bulbs are selected, there are exactly how many possible different color sequences of the three lights?

(A) one
(B) two
(C) three
(D) four
(E) five

11. If no two lights are assigned light bulbs that are the same color as each other, then which one of the following could be true?

(A) Light I is green, and light 2 is purple.
(B) Light I is green, and light 2 is yellow.
(C) Light I is purple, and light 2 is yellow.
(D) Light I is yellow, and light 2 is green.
(E) Light I is yellow, and light 2 is purple