Hi fourteenstix,
What is the source of this question? I ask because the "intent" of this question might not match the "logic" of this question. The information at the beginning of the prompt is "causal" but only deals with tiles that PRECEDE other tiles; we have to deduce what tiles can FOLLOW other tiles. We know what comes immediately before a red (a yellow) and we know what comes immediately before a yellow (a green), but we're not told what comes before a green.
Up-Front Deductions:
A Green can be followed by another Green or a Yellow (but not a Red)
A Yellow can be followed by a Green or a Red (but not a Yellow)
A Red can be followed by a Green (but not a Yellow or Red)
We're asked for the 24th Tile....
Fact 1: 18th = NOT Yellow, so 18th = Green OR Red
If 18th = Red
we would have G, G, G, G, G to infinity, so the 24th Tile = GREEN
If 18th = Green
we COULD have G, G, G, G, G, Y, so the 24th Tile = YELLOW
Inconsistent = INSUFFICIENT
Fact 2: 19th is NOT Green, so 19th = Yellow OR Red
If 19th = Red
we would have G, G, G, G, G, so the 24th Tile = GREEN
If 19th = Yellow
we could have R, G, G, G, Y so the 24th Tile = YELLOW
Inconsistent = INSUFFICIENT
Combining Facts:
18th = Green OR Red
19th = Yellow OR Red
Since Red can only be followed by GREEN, the 18th Term CAN'T be Red!
So, 18th = Green and
19th = Yellow
we could have G, G, G, G, G, so the 24th = GREEN
we could have G, G, G, G, Y, so the 24th = YELLOW
Inconsistent = INSUFFICIENT
Final AnswerE
GMAT assassins aren't born, they're made,
Rich
