Explanation

Use nCr or nPr to find probability:

P = (# of favorable outcomes) / (# of total outcomes)

Example:

• 5 cards, choose 2 hearts from 3 hearts

• Total ways = 5C2 = 10

• Favorable = 3C2 = 3
  P = 3/10

Quiz

1. What is the probability formula with combinatorics?

2. 4 choose 2 out of 6 total → probability = ?

3. Is order important here?

4. What does favorable outcomes mean?

5. Can you use permutations for unordered events?

Answer Key

1. P = favorable / total = nCr(fav) / nCr(total)

2. Favorable = 4C2 = 6, Total = 6C2 = 15 → P = 6/15 = 0.4

3. No

4. Outcomes that match your event

5. No