- #1

nontradstuden

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1) Given 20 men and 20 women, how many groups of 12 can you make with 6 men and 6 women.

I said 20.Combination.6 * 20.Combination.6.

2) given S= {1, 2, 4, 5, 7}, you will choose 3 randomly from the set. What's the probability of getting an even number greater than 500?

I said 12 / 5.Permutation.3.

How I got 12:

1. 3 ways of having 5 first, 2 last.

2. 3 ways of having 5 first, 4 last.

3. 3 ways of having 7 first, 2 last.

4. 3 ways of having 7 first, 4 last.

Added it up to get 12. I then divided it by a permutation because order is important?...

3) What is the probability that two randomly chosen people were both not born in June?

I said P(First not born in June ^ Second not born in June)= (11/12) * (11/12)

Is my counting right? Thanks for your help.