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805+ (Hard)|   Algebra|   Arithmetic|      
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A scanning code consists of a 7 times 7 grid of squares, with some of 17 Nov 2018, 10:07
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Difficulty:

95% (hard)

Question Stats:

28% (01:58) correct 72% (02:11) wrong based on 96 sessions

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GMATbuster's Weekly Quant Quiz#9 Ques 5


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A scanning code consists of a 7 times 7 grid of squares, with some of its squares colored black and the rest colored white. There must be at least one square of each color in this grid of 49 squares. A scanning code is called symmetric if its look does not change when the entire square is rotated by a multiple of 90 deg counterclockwise around its center, nor when it is reflected across a line joining opposite corners or a line joining midpoints of opposite sides. What is the total number of possible symmetric scanning codes?

A) 510
B) 1022
C) 8190
D) 8192
E) 65534
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B
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A scanning code consists of a 7 times 7 grid of squares, with some of 19 Nov 2018, 07:15
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Official Solution




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Sol5.jpg [ 128.42 KiB | Viewed 5168 times ]
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A scanning code consists of a 7 times 7 grid of squares, with some of 19 Nov 2018, 08:02
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I don't think this a GMAT type question.
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A scanning code consists of a 7 times 7 grid of squares, with some of 21 Nov 2018, 22:24
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GMATbuster's Weekly Quant Quiz#9 Ques 5


For Questions from earlier quizzes: Click Here

A scanning code consists of a 7 times 7 grid of squares, with some of its squares colored black and the rest colored white. There must be at least one square of each color in this grid of 49 squares. A scanning code is called symmetric if its look does not change when the entire square is rotated by a multiple of 90 deg counterclockwise around its center, nor when it is reflected across a line joining opposite corners or a line joining midpoints of opposite sides. What is the total number of possible symmetric scanning codes?

A) 510
B) 1022
C) 8190
D) 8192
E) 65534
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This is a God level question. I have to be a super-human to get this within 2 mins.
:please :please :please
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A scanning code consists of a 7 times 7 grid of squares, with some of 22 Nov 2018, 08:25
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The GMAT is an unpredictable exam
So one needs to prepare for unexpected, especially if one is aiming to hit the 51 mark.

Whether is it a potential GMAT Question?
WHY NOT?
This question is not using any higher mathematics nor highly calculation oriented. Yes, it is a but different from the common types of GMAT questions.
Yes, this question needs out of box thinking so it might take more than 2 minutes to solve. But some GMAT questions do need more than 2 minutes and some even need to be guessed.

Expect the unexpected in GMAT.

Happy Learning
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A scanning code consists of a 7 times 7 grid of squares, with some of 20 Jun 2024, 12:06
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