Matching colour counts in two pairs of jellybeans
Question
A bag holds green and yellow jellybeans. Four are taken out one after another at random without replacement. What is the probability that the first two drawn and the last two drawn contain the same colours as multisets (order within each pair ignored)? For example, GYYG and GGGG qualify while GGYG does not.
Short answer
. Either all four beans share a colour, or each pair holds one green and one yellow (in possible orders). Ordered draws give all-green and all-yellow sequences plus mixed ones, out of , which simplifies to .
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- Counting and Combinatorics
- Continuous Random Variables and Probability Density Functions
- Cumulative Distribution Functions
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