Combinations

                     Lesson 1

Problem:   In the hat, there are 7 rabbits,

        4 handkerchiefs and 6 playing cards.

        If three items are selected randomly without replacement,

        what is the probability of getting: 

Step 1:    2 playing cards and 1 handkerchief.

Step 2:  (₆C₂ × ₄C₁) / ₁₇C₃ = (15 × 4) / 680 = 15/170

Step 3: Answer: 15/170

                                                            Try two practice problems:

In a group there are 3 boys, 6 girls and 3 teacher. If three people are chosen, what is the probability of choosing:

A. 2 boy and 1 girl

.

B. 3 boys and 1 teacher.

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