A) C(4,2)C(36,0)/C(40,2)
B) C(8,2)C(32,0)/C(40,2)
C) C(10,1)C(18,1)C(12,0)/C(40,2)
D) C(18,0)C(22,2)/C(40,2)
Rachel C.
asked • 03/28/21Probability - When to use Combination v. Permutation
Could someone clarify if a permutation is supposed to be used to solve a problem with no replacement included, using the following question as an example to explain?
Jacob has 10 rap, 18 rock, 8 country, and 4 pop songs in his playlist. Two are selected at random. Find each probability:
A. P (2 pop) B. P(2 country C. P(1 rap, 1 rock) D. P(not rock)
(sorry for the awkward phrasing)
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Rachel C.
Hi, Thanks so much for the help! However, for part C. the answer key provided by my teacher states the correct answer is 3/26, which can be found using P(10,1)P(18,1)/P(40,2), which is what I was mainly confused about in my original post. I don't understand why a permutation (nPr) is used here when the order of the selected songs does not mater. Could you help clarify this?03/28/21