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OG -12 Question

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by parulmahajan89 » Wed Aug 15, 2012 12:44 pm
87. A necklace is made by stringing N individual beads
together in the repeating pattern red bead, green
bead, white bead, blue bead, and yellow bead. If the
necklace design begins with a red bead and ends with
a white bead, then N could equal
(A) 16
(B) 32
(C) 4 1
(D) 54
(E) 68

Please provide explanation. Can we use permutation here?

Thank you
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Source: — Problem Solving |

by rijul007 » Wed Aug 15, 2012 1:19 pm
parulmahajan89 wrote:87. A necklace is made by stringing N individual beads
together in the repeating pattern red bead, green
bead, white bead, blue bead, and yellow bead. If the
necklace design begins with a red bead and ends with
a white bead, then N could equal
(A) 16
(B) 32
(C) 4 1
(D) 54
(E) 68

Please provide explanation. Can we use permutation here?

Thank you
The pattern would look like this
Red Green White Blue Yellow Red Green White Blue Yellow Red Green White Blue Yellow .........
First bead = Red
Last bead = White
Postions of white bead = 3,8,13,...,N
According to the above series,
N = 3 + a*5
where a is an integer

From the answer choices, Option E satisfies the formula.
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