The following table summarizes the result of a poll taken of CEOs and analysts about the economic impact of a pending piece of legislation. Group PredictPositiveImpact PredictNegativeImpact CEOs 40 30 Analysts 70 60 What is the probability that a randomly selected individual from this group whill be either an analyst of someone who thinks this legislation will have a positive impact on economy ? A>0.75 B>0.80 C>0.85 D>0.90 Please explain the results. thanks

There are 130 analysts. 110 People think it will have a positive impact. But there are 70 who are analysts and think a positive impact. 130 + 110 - 70 = 170. 170/200 = 0.85 C (200 is the total no. of people)

Got it. P(A or B) = P(A)+P(B) -P(AB) thanks

koppcha Wrote: ------------------------------------------------------- > Got it. P(A or B) = P(A)+P(B) -P(AB) thanks addition rule, nice! I hate probability. There are 6 rules, recall ------------------------------------- multi multi for ind events addition total prob bayes rule conditional

Well, wouldn’t the answer be B… greater than 80%. The answer is a hard 85%. So, to be a pain, C is wrong.