Chapter 8: Q102S (page 452)
Find the numerical value of
a.6! b.c. d.e.0!
Short Answer
The results for the given numerical values are as follows:
- 720
- 10
- 10
- 20
- 1
Chapter 8: Q102S (page 452)
Find the numerical value of
a.6! b.c. d.e.0!
The results for the given numerical values are as follows:
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Get started for freeFind a value of the standard normal random variable z, call it , such that
Bankruptcy effect on U.S. airfares. Both Delta Airlines and USAir filed for bankruptcy. A study of the impact of bankruptcy on the fares charged by U.S. airlines was published in Research in Applied Economics (Vol. 2, 2010). The researchers collected data on Orlando-bound airfares for three airlines—Southwest (a stable airline), Delta (just entering bankruptcy at the time), and USAir (emerging from bankruptcy). A large sample of nonrefundable ticket prices was obtained for each airline following USAir’s emergence from bankruptcy, and then a 95% confidence interval for the true mean airfare was obtained for each. The results for 7-day advance bookings are shown in the accompanying table.
a. What confidence coefficient was used to generate the confidence intervals?
b. Give a practical interpretation of each of the 95% confidence intervals. Use the phrase “95% confident” in your answer.
c. When you say you are “95% confident,” what do you mean?
d. If you want to reduce the width of each confidence interval, should you use a smaller or larger confidence coefficient?
Question: Independent random samples n1 =233 and n2=312 are selected from two populations and used to test the hypothesis against the alternative
.a. The two-tailed p-value of the test is 0.1150 . Interpret this result.b. If the alternative hypothesis had been , how would the p-value change? Interpret the p-value for this one-tailed test.Buy-side vs. sell-side analysts' earnings forecasts. Refer to the Financial Analysts Journal (Jul. /Aug. 2008) study of financial analysts' forecast earnings, Exercise 2.86 (p. 112). Recall that data were collected from buy-side analysts and forecasts made by sell-side analysts, and the relative absolute forecast error was determined for each. The mean and standard deviation of forecast errors for both types of analysts are given in the table.
a. Construct a confidence interval for the difference between the mean forecast error of buy-side analysts and the mean forecast error of sell-side analysts.
b. Based on the interval, part a, which type of analysis has the greater mean forecast error? Explain.
c. What assumptions about the underlying populations of forecast errors (if any) are necessary for the validity of the inference, part b?
Optimal goal target in soccer. When attempting to score a goal in soccer, where should you aim your shot? Should you aim for a goalpost (as some soccer coaches teach), the middle of the goal, or some other target? To answer these questions, Chance (Fall 2009) utilized the normal probability distribution. Suppose the accuracy x of a professional soccer player’s shots follows a normal distribution with a mean of 0 feet and a standard deviation of 3 feet. (For example, if the player hits his target,x=0; if he misses his target 2 feet to the right, x=2; and if he misses 1 foot to the left,x=-1.) Now, a regulation soccer goal is 24 feet wide. Assume that a goalkeeper will stop (save) all shots within 9 feet of where he is standing; all other shots on goal will score. Consider a goalkeeper who stands in the middle of the goal.
a. If the player aims for the right goalpost, what is the probability that he will score?
b. If the player aims for the center of the goal, what is the probability that he will score?
c. If the player aims for halfway between the right goal post and the outer limit of the goalkeeper’s reach, what is the probability that he will score?
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