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the number of possible permutations for the assessment

Monoxdifly

Well-known member
Aug 6, 2015
271
There are 4 questions in the assessment. In order not to repeat questions in an assessment, question 1 could be any of 13 questions, question 2 any of 21 questions, question 3 any one of 14 questions and question 4 any one of 12 questions. How do I calculate the number of possible permutations for the assessment? Is it 13 × 18 × 13 × 10?
 

HallsofIvy

Well-known member
MHB Math Helper
Jan 29, 2012
1,151
There are 4 questions in the assessment. In order not to repeat questions in an assessment, question 1 could be any of 13 questions, question 2 any of 21 questions, question 3 any one of 14 questions and question 4 any one of 12 questions. How do I calculate the number of possible permutations for the assessment? Is it 13 × 18 × 13 × 10?
We need to clarify. Are the 13 possible questions for #1 distinct from the 21 possible questions for #2? There are no questions in two different question pools? If so then, by the "fundamental counting principle", the number of tests, differing by at least one question, is 13(21)(14)(21).
I have no idea where you got "18 x 13 x 10". Also those are not "permutations" since you are not changing the order of the questions.
 

Monoxdifly

Well-known member
Aug 6, 2015
271
Since that's the whole question, probably we should just assume that those groups non-intersecting. Thanks.