SOLUTION: four tickets are drawn from tickets number 1-30 inclusive. Determine the probability that the tickets marked 1 and 2 are among the four

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Question 1119199: four tickets are drawn from tickets number 1-30 inclusive. Determine the probability that the tickets marked 1 and 2 are among the four
Answer by greenestamps(13334) About Me  (Show Source):
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The total number of ways of choosing 4 of the 30 tickets is 30 choose 4:

%2830%2A29%2A28%2A27%29%2F%284%2A3%2A2%2A1%29

The number of ways of choosing both the number 1 and 2 tickets and any 2 of the other 28 tickets is (2 choose 2) times (28 choose 2):

1+%2A+%28%2828%2A27%29%2F%282%2A1%29%29

The probability is then the ratio of those two numbers of ways:

or about 0.0138.