Suppose we want to choose 5 objects, without replacement, from 15 distinct objects.(a) How many ways can this be done, if the order of the choices does not matter?(b) How many ways can this be done, if the order of the choices matters?
Q. Suppose we want to choose 5 objects, without replacement, from 15 distinct objects.(a) How many ways can this be done, if the order of the choices does not matter?(b) How many ways can this be done, if the order of the choices matters?
Calculate combinations: Calculate the number of ways to choose 5 objects from 15 without considering the order (combinations).Reasoning: Use the combination formula nCr=r!(n−r)!n!, where n is the total number of objects and r is the number of objects to choose.Calculation: \(15\)C\(5\) = \frac{\(15\)!}{\(5\)!(\(15\)\(-5\))!} = \frac{\(15\)!}{(\(5\)! \cdot \(10\)!)} = \frac{(\(15\) \cdot \(14\) \cdot \(13\) \cdot \(12\) \cdot \(11\))}{(\(5\) \cdot \(4\) \cdot \(3\) \cdot \(2\) \cdot \(1\))} = \(3003\).
Calculate permutations: Calculate the number of ways to choose \(5\) objects from \(15\) considering the order (permutations).\(\newline\)Reasoning: Use the permutation formula \(nPr = \frac{n!}{(n-r)!}\), where \(n\) is the total number of objects and \(r\) is the number of objects to choose.\(\newline\)Calculation: 15P5 = \frac{15!}{(15−5)!} = \frac{15!}{10!} = (15 \times 14 \times 13 \times 12 \times 11) = 360360.
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