16. Counting

Question 1

Multiplication Principle

(rule of product)

Answer 1

If there are a ways of doing something and b ways of doing another thing, then there are a • b ways of performing both actions.

Question 2

Factorials used in counting

Answer 2

The number of ways “n” objects can be ordered is n!

Question 3

Relationship between Permutations and Combinations

Answer 3

A Permutation is an ordered combiation.

Question 4

Permutation

Formula

Answer 4

A set of objects in which position (or order) is important.

_nP_r = n! / (n – r)!

Question 5

Combination

Formula

Answer 5

A set of objects in which position (or order) is not important.

_nC_r = n! / (n – r)! r!

Question 6

Answer 6

The number of ways r objects can be chosen from n.