Example class 4

Example class 4 - 3. In a cannery, assembly lines I, II,...

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The University of Hong Kong Department of Statistics and Actuarial Science STAT 1301 Probability and Statistics I Example Class 4 1. The probability that a person in the United States has type O+ blood is 38%. Three unrelated people in the U.S. are selected at random. a) Find the probability that all three have type O+ blood. b) Find the probability that none of the three has type O+ blood. c) Find the probability that at least one of the three has type O+ blood. Ans (a) 0.38*0.38*0.38; (b) 0.62*0.62*0.62 (c) 1- P(None) 2. In a T-maze, a rat is given food if it turns left and an electric shock if it turns right. The rat has 50/50 chance to turn either way only in the 1 st trial. Then if it receives food on the first trial, the probability is 0.72 that it will turn left on the next trial, and if it receives a shock on the first trial, the probability is 0.88 that it will turn left on the next trial. If a rat turns left on the second trial, what is the probability that it turned left also on the first trial? Ans (0.5*0.72)/(o.5*0.72+0.5*0.88)
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Unformatted text preview: 3. In a cannery, assembly lines I, II, and III account, respectively, for 37%, 42% and 21% of total output. If 0.6% of the cans from assembly line I are improperly sealed, while the corresponding percentages for assembly lines II and III are 0.4% and 1.2%, what is the probability that an improperly sealed can came from assembly line III? Ans (0.21*1.2%)/(0.37*0.6%+0.42*0.4%+0.21*0.2%) 4. Two drugs A and B are given to 200 patients in an experiment. The dealer of drug A has suggestion treating 30 men and 70 women patients with drug A. A quota of another 100 patients is allocated to treatment of drug B. The following table shows the recovery probabilities of treated patients with the two drugs. Men Woman A 0.3 0.7 B 0.2 0.6 a) Show the recovery probabilities for drug A is higher for both Men and Women. b) In order to claim a higher recovery rate, at least how many women should be treated by the drug dealer of B? Ans (b) > 95...
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