Data Sufficiency

OA after a few folks reply.

In a single row of yellow, green and red colored tiles, every red tile is preceded immediately by a yellow tile and every yellow tile is preceded immediately by a green tile. What color is the 24th tile in the row?

(1) The 18th tile in the row is not yellow.

(2) The 19th tile in the row is not green.

Since Red is preceded by yellow and yellow by green , the 01st tile be either yellow or green .cannot be red because red is always preceded by yellow.

1 The seq can be YRG or GYR .In either case 18th tile cannot be yellow - multiple of 3 - so the 18th tile will be G or R
INSUFF

2 SUFF 19th tile not G so 18th tile is G therefore 24th tile is G

Bhandaripreeti wrote:Since Red is preceded by yellow and yellow by green , the 01st tile be either yellow or green .cannot be red because red is always preceded by yellow.

1 The seq can be YRG or GYR .In either case 18th tile cannot be yellow - multiple of 3 - so the 18th tile will be G or R
INSUFF

2 SUFF 19th tile not G so 18th tile is G therefore 24th tile is G

In 1 above, when yellow is preceded by Green, how can the series take YGR pattern?
and can you pls elaborate how the answer is B?

The answer should be E

OA is E. Our minds are too programmed to think of this
in terms of repeating patterns...

Here's the explanation --


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.

OA is E. Our minds are too programmed to think of this
in terms of repeating patterns...

Here's the explanation --


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 . . .

Too good explnation..You ROCK "jayhawk2001". may I know you're from which part of the globe?

mendiratta wrote: Too good explnation..You ROCK "jayhawk2001". may I know you're from which part of the globe?

Actually its the explanation from MGMAT. I just cut-pasted it 8)

jayhawk2001 wrote:

mendiratta wrote: Too good explnation..You ROCK "jayhawk2001". may I know you're from which part of the globe?

Actually its the explanation from MGMAT. I just cut-pasted it 8)

... jay dude u still rawk ... good to see ur active participation on the forum ...