The following is the explanation that i found from MANHATTAN GMAT:
Can someone explain better ?
It is tempting to view the information in the question as establishing a pattern as follows:
Green, Yellow, Red, Green, Yellow, Red, . . .
However, consider that the following non-pattern is also possible:
Green, Yellow, Red, Green, Green, Green, Green . . .
(1) INSUFFICIENT: This tells us that the 18th tile is Green or Red but this tells us nothing about the 24th tile. Statement (1) alone is NOT sufficient.
(2) INSUFFICIENT: This tells us that the 19th tile is Yellow or Red but this tells us nothing about the 24th tile. Statement (2) alone is NOT sufficient.
(1) AND (2) INSUFFICIENT: Together, the statements yield the following possibilities for the 18th and 19th tiles:
GY, GR, RY, or RR
However, only GY adheres to the rules given in the question. Thus, we know that tile 18 is green and tile 19 is yellow. However, this does not help us to determine the color of the next tile, much less tile 24 (the one asked in the question). For example, the next tile (tile 20) could be green or red. Thus, the statements taken together are still not sufficient.
The correct answer is E.
Last edited by
karthikpandian19 on Tue Jan 10, 2012 4:51 am, edited 1 time in total.
