In a box of 10 electrical parts, 2 are defective. (a)If you choose one part at random from the box, what is the probability that

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问题 In a box of 10 electrical parts, 2 are defective.
(a)If you choose one part at random from the box, what is the probability that it is not defective?
(b)If you choose two parts at random from the box, without replacement, what is the probability that both are defective?