Have to clear the fog of confusion!

Txroadrunner

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Apr 27, 2013
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A student studying for a test knows 16 of 26 vocabulary words. If the test contains 10 words from the study list, what is the probability that at least 8 will be ones the student knows?
This question is posted, but duplication of a number, absent explanation, is keeping me from figuring out how to solve my problem... The issue is 10.
The solution is C(16,8)C(10,2)+C(16,9)C(10,1)+C(16,10)C(10,0)/C(26,10).

Does this translate to "# known questions,#on test" x "#not known,#not on test"...?
It is just a coincidence that the total number of questions on the test is the same as the number of vocabulary words not known from the study list. The same number represents two clearly different things...
Can someone please clear this up for me?
 
Got my answer... don't know how to close post.

Got my answer...
A student studying for a test knows 16 of 26 vocabulary words. If the test contains 10 words from the study list, what is the probability that at least 8 will be ones the student knows?
This question is posted, but duplication of a number, absent explanation, is keeping me from figuring out how to solve my problem... The issue is 10.
The solution is C(16,8)C(10,2)+C(16,9)C(10,1)+C(16,10)C(10,0)/C(26,10).

Does this translate to "# known questions,#on test" x "#not known,#not on test"...?
It is just a coincidence that the total number of questions on the test is the same as the number of vocabulary words not known from the study list. The same number represents two clearly different things...
Can someone please clear this up for me?
 
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