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Marbles count

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Marbles count

by psm12se » Sat Dec 07, 2013 8:19 am
Julie is putting M marbles in a row in a repeating pattern: blue, white, red, green, black, yellow, pink. If the row begins with blue marble and ends with red marble, then which of the following could be the value of M?

A. 22
B. 30
C. 38
D. 46
E. 54

OA: C
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by Uva@90 » Sat Dec 07, 2013 8:37 am
psm12se wrote:Julie is putting M marbles in a row in a repeating pattern: blue, white, red, green, black, yellow, pink. If the row begins with blue marble and ends with red marble, then which of the following could be the value of M?

A. 22
B. 30
C. 38
D. 46
E. 54

OA: C
Hi Psm12se,
Question states that Pattern goes like this,
blue ---> Starting
white
red ---> Ending.
green
black
yellow
pink.

So, M = 7k+3(7 is the total number of colors, 3 is since finishing with third color)
So among the options given above which number is divisible by 7 after subtracting by 3.
there is only one option.
i.e. 38

Answer is C

Regards,
Uva.
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by theCodeToGMAT » Sat Dec 07, 2013 10:06 am
B-W-R-G-B-Y-P

The pattern is 7M + 3

If we compare this pattern with the answer choices to find the INT value of "M":

Only [spoiler]{C}[/spoiler] .. because 38 ==> 7(5) + 3
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by Brent@GMATPrepNow » Sat Dec 07, 2013 10:47 am
psm12se wrote:Julie is putting M marbles in a row in a repeating pattern: blue, white, red, green, black, yellow, pink. If the row begins with blue marble and ends with red marble, then which of the following could be the value of M?

A. 22
B. 30
C. 38
D. 46
E. 54

A: C
Let's list a few and look for a PATTERN:

Marble 1: blue
Marble 2: white
Marble 3: red
Marble 4: green
Marble 5: black
Marble 6: yellow
Marble 7: pink
Marble 8: blue
Marble 9: white
Marble 10: red
Marble 11: green
Marble 12: black
Marble 13: yellow
Marble 14: pink
Marble 15: blue
Marble 16: white
Marble 17: red
.
.
.
As you can see, the position of the red marble is 3 plus some multiple of 7
In other words, the position of the red marble will equal 7n + 3
Since answer choice [spoiler]C (38)[/spoiler] can be written as 7(5) + 3, it must be the correct answer.

Cheers,
Brent
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by Brent@GMATPrepNow » Sat Dec 07, 2013 10:48 am
psm12se wrote:Julie is putting M marbles in a row in a repeating pattern: blue, white, red, green, black, yellow, pink. If the row begins with blue marble and ends with red marble, then which of the following could be the value of M?

A. 22
B. 30
C. 38
D. 46
E. 54

A: C
Looks like my post was posted twice.

Cheers,
Brent
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