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Necklace
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MBA.Aspirant
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ntamhane
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Number of Red beads in the Necklace - 14
Number of Green beads in the Necklace - 14
Number of Whit beads in the Necklace - 14
Number of Blue beads in the Necklace - 13
Number of Yellow beads in the Necklace - 13
No. of ways to select 1 bead from 68 = 68
No. of ways to select 1 bead from 14 read = 14
Probability of selecting a read bead = [spoiler]14/68 = 7/34[/spoiler]
Number of Green beads in the Necklace - 14
Number of Whit beads in the Necklace - 14
Number of Blue beads in the Necklace - 13
Number of Yellow beads in the Necklace - 13
No. of ways to select 1 bead from 68 = 68
No. of ways to select 1 bead from 14 read = 14
Probability of selecting a read bead = [spoiler]14/68 = 7/34[/spoiler]
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Geva@EconomistGMAT
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This explanation is indeed correct.ntamhane wrote:Number of Red beads in the Necklace - 14
Number of Green beads in the Necklace - 14
Number of Whit beads in the Necklace - 14
Number of Blue beads in the Necklace - 13
Number of Yellow beads in the Necklace - 13
No. of ways to select 1 bead from 68 = 68
No. of ways to select 1 bead from 14 read = 14
Probability of selecting a read bead = [spoiler]14/68 = 7/34[/spoiler]
@Aspirant, what was your difficulty here?
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Ian Stewart
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I have an issue with the wording of the question. Necklaces are circular; how can you identify where the pattern of beads begins, if there is no 'first bead' in a circular pattern? The question designer ought to have found a different setup in which the pattern is in a line or a row, rather than in a circle. Still, based on what I imagine were the intentions of the question designer, ntamhane's explanation above is perfect.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
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