Question

S={1,2,3,4}, A={1,2}, write A

Answer 1

A= {1, 2}

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Answer 2

A contains the multiples of 2, whereas S contains natural numbers.

Now, n(A) = 2, n(S) = 4

P(A) = n(A) / n(S)

P(A) = 2 / 4 = 1 / 2