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Let S = {1, 2, ...., 20}. A subset B of S is said to be "nice", if the sum of the elements of B is 203. Then the probability that a randonly chosen subset of S is "nice" is :

1. 20 2 5
2. 20 2 7
3. 20 2 4
4. 20 2 6

Correct answer: 20 2 5

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