A rectangular wall is completely filled with square tiles of 9 rows and 13 columns. The tiles are of equal area. Each tile is yellow or orange, and no tiles with a common side are the same color. If the wall contains more yellow tiles than orange tiles, how many yellow tiles does the wall contain?
A. 57
B. 58
C. 59
D. 60
E. 61
The OA is C.
Please, can anyone assist me with this PS questions? I need help to solve it. Thanks!
A rectangular wall is completely filled with square tiles of
This topic has expert replies
-
- Moderator
- Posts: 2209
- Joined: Sun Oct 15, 2017 1:50 pm
- Followed by:6 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
. . . and no tiles with a common side are the same colorBTGmoderatorLU wrote:A rectangular wall is completely filled with square tiles of 9 rows and 13 columns. The tiles are of equal area. Each tile is yellow or orange, and no tiles with a common side are the same color. If the wall contains more yellow tiles than orange tiles, how many yellow tiles does the wall contain?
A. 57
B. 58
C. 59
D. 60
E. 61
To meet this condition, it MUST be the case that the yellow and orange squares are arranged in a checkerboard pattern.
In such a checkerboard pattern, the colors alternate yellow, orange, yellow, orange, yellow, orange etc
This means half of the squares are orange and half are yellow.
HOWEVER, the wall has 9 rows and 13 columns, which means the TOTAL number of tiles = (9)(13) = 117
This is an odd number, so there will be one extra tile.
. . . the wall contains more yellow tiles than orange tiles
So, there must be one extra YELLOW tile.
Let x = number of orange tiles
So, x+1 = number of yellow tiles
There are 117 tiles, so we can write: x + (x + 1) = 117
Simplify: 2x + 1 = 117
Solve, x = 58
So, there are 58 orange tiles and 59 yellow tiles.
Answer: C
Cheers,
Brent