Statistics > EXAM > PRACTISE MID TERM 1 KEY FOR Stat 100A -Intro Probability-ALL ANSWERS CORRECT (All)

PRACTISE MID TERM 1 KEY FOR Stat 100A -Intro Probability-ALL ANSWERS CORRECT

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Question 1. A computer student can repeat an examination until it is passed, but it is allowed to attempt the examination at most four times. The number of outcomes in the sample space of possible out... comes is (a) 6 (b) 5 (c) 2 (d) 10 (e) 4 Solution 1. List all the outcomes in the sample space S. S = {P, PcP, PcPcP, PcPcPcP, PcPcPcPc} Question 2. A total of 500 married working couples were polled about their annual salaries, with the following information resulting: • In 212 couples, both the husband and the wife made less than $25000. • In 198 couples, the wife made less than $25000, but the husband made $25000 or more. • In 36 couples the wife made $25000 or more but the husband made less than $25000 • in 54 couples both the husband and the wife made $25000 or more. The probability that the husband earns less than $25000 is (a) 0.614 (b) 0.496 (c) 0.424 (d) 0.517 (e) 0.854 Solution 2. (212+36)/500=0.496. Question 3. Suppose that 10% of a large lot of apples is damaged. Suppose a customer randomly selects and then purchases four apples. If an apple is damaged, the customer will complaint. To keep the customer satisfied, the store has a policy of replacing any damaged item (here the apple) and giving the customer a coupon for future purchases. The cost of this program has, through time, been found to be C = 0.5X2, where X denotes the number of defective apples in the purchase of four. Find the expected cost when a customer randomly selects four apples from the lo [Show More]

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