Unit 9 (Probability)

Question 1

Formula for combinations?

Answer 1

nCr= n!/r!(n-r)! where n is # of distinguishable choices and r is # of terms

Question 2

Formula for permutations?

Answer 2

nPr= n!/(n-r)! where n is # of distinguishable choices and r is # of terms

Question 3

What is the difference between a combination and a permutation?

Answer 3

The main difference between combinations and permutations lies in whether the order of selection matters. In combinations, the order is not important, meaning that selecting items in a different order doesn’t create a distinct grouping. In permutations, the order does matter, and different orderings are considered distinct arrangements. A permutation is an arrangement of objects where the order of arrangement is important. For example, if you have the letters A, B, and C, the permutations ABC, ACB, BAC, BCA, CAB, and CBA are all distinct.A combination is a selection of objects where the order of selection is not important. For example, if you have the letters A, B, and C, the combinations ABC, ACB, BAC, BCA, CAB, and CBA are all considered the same combination (simply the set {A, B, C}).

Question 4

Are there often more combinations or permutations?

Answer 4

permutations.

Question 5

9C2: how is this said? what does it mean?

Answer 5

Nine chose two. It means choosing two options from a set of nine.

Question 6

Make sure to check for words like repeating, to determine whether or not combination or permutation