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Counting: Permutations & Combinations · Easy Worksheet 2

Counting: Permutations & Combinations — Easy Worksheet 2

Grade 11 · Whoobee    Name: ____________________   Date: __________

Find each number. Decide first whether order matters.

How to solve

Counting principle: multiply the number of choices at each step. n! = n × (n - 1) × ... × 1 counts ways to arrange n things. When order matters (1st, 2nd, 3rd), use P(n, r) = n! ÷ (n - r)!. When order does not matter (a group or committee), use C(n, r) = n! ÷ (r! × (n - r)!).

Example

You have 5 shirts, 3 pairs of pants and 3 pairs of shoes. How many different outfits can you make?

Answer: 45

right so far
1 You have 3 shirts, 4 pairs of pants and 3 pairs of shoes. How many different outfits can you make?
2 Evaluate 4!
3 In how many different orders can 3 books be placed on a shelf?
4 You have 3 shirts, 4 pairs of pants and 2 pairs of shoes. How many different outfits can you make?
5 Evaluate 3!
6 In how many different orders can 7 books be placed on a shelf?
7 You have 5 shirts, 2 pairs of pants and 3 pairs of shoes. How many different outfits can you make?
8 Evaluate 6!
9 In how many different orders can 4 books be placed on a shelf?
10 You have 4 shirts, 3 pairs of pants and 3 pairs of shoes. How many different outfits can you make?

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