答案和详解如下: Answer 21 The correct answer was B) 2.7%. 4.86 / (360/240) = 2.7%. This question tested from Session 2, Reading 6, LOS d, (Part 2)
Answer 22 The correct answer was A) greater than 25% is 0.32. Sixty-eight percent of all observations fall within +/- one standard deviation of the mean of a normal distribution. Given a mean of 15 and a standard deviation of 10, the probability of having an actual observation fall within one standard deviation, between 5 and 25, is 68%. The probability of an observation greater than 25 is half of the remaining 32%, or 16%. This is the same probability as an observation less than 5. Because 95% of all observations will fall within 20 of the mean, the probability of an actual observation being greater than 35 is half of the remaining 5%, or 2.5%. This question tested from Session 3, Reading 10, LOS a
Answer 23 The correct answer was D) 48%. Given a set of prior probabilities for an event, Bayes’ formula is used to update the probability of the event, in this case the probability that the prospect whom we already know purchased the product has an MBA. Bayes’ formula says to divide the "probability of new information given the event" by the "unconditional probability of new information," and multiply that result by the "prior probability of the event." In this case, P(prospect has an MBA) = 0.6 is divided by P(prospect buys the product), and the result is multiplied by P(an MBA buys the product) = 0.5. To find the unconditional probability of a prospect buying the product: 60% have MBAs, of whom 50% buy the product, and 40% are undergraduates, of whom 80% buy the product. So P(prospect buys the product) = (0.6)(0.5) + (0.4)(0.8) = 0.62. The updated probability is therefore (0.6/0.62) × 0.5 = 0.484 or 48.4%. This question tested from Session 2, Reading 8, LOS a
Answer 24 The correct answer was B) Based on the Sharpe ratio, the performance of the Smith portfolio is preferable to the performance of the Johnson portfolio. The Sharpe ratio for the Johnson portfolio is (1.4 - 0.3)/10.8 = 0.1019. The Sharpe ratio for the Smith portfolio is (1.2 - 0.3)/6.8 = 0.1324. The Smith portfolio has the higher Sharpe ratio, or greater excess return per unit of risk. This question tested from Session 2, Reading 7, LOS h, (Part 2)
Answer 25 The correct answer was D) 0.707. The central limit theorem tells us that for a population with a mean µ and a finite variance σ2, the sampling distribution of the sample means for a sample of size n will be approximately normally distributed with a mean equal to µ and a variance equal to σ2/n, no matter the distribution of the population, assuming a large sample size. The standard error of the sample mean when the standard deviation of the population is known is: σsample mean = σ/√n = 5/√50 = 0.707 This question tested from Session 3, Reading 10, LOS e
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