I just want to use "stupid". Go ask a statistics professor in a college. The two questions looked different, but they have the same answer.www.ddhw.com A common mistake for students who learn probabilty theory: Instantiate instances based on the condition given, then calculate. Rather, you should instantiate all instances first, then determine the rate by conditions. Therefore, your first question, you should have 4 instances rather than 3, so that it should be 50% rather thahn 1/3, don't be fooled by the condition "one of then is a boy". Anyway, I don't know why I bother tell you this. Please just go to ask a stat professor. www.ddhw.com
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