(a) Use a calculator or appropriate computer software to find x for the preceding data. (Round your answer to two decimal places.) thousand dollars (b) Let us say that the preceding data are representative of the entire sector of (successful) financial services corporations. Find a 75% confidence interval for μ, the average annual profit per employee for all successful banks. (Round your answers to two decimal places.) lower limit thousand dollars upper limit thousand dollars (c) Let us say that you are the manager of a local bank with a large number of employees. Suppose the annual profits per employee are less than 30 thousand dollars per employee. Do you think this might be somewhat low compared with other successful financial institutions? Explain by referring to the confidence interval you computed in part (b). Yes. This confidence interval suggests that the bank profits are less than those of other financial institutions.Yes. This confidence interval suggests that the bank profits do not differ from those of other financial institutions. No. This confidence interval suggests that the bank profits are less than those of other financial institutions.No. This confidence interval suggests that the bank profits do not differ from those of other financial institutions.
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
Jobs and productivity! How do banks rate? One way to answer this question is to examine annual profits per employee. The following is data about annual profits per employee (in units of 1 thousand dollars per employee) for representative companies in financial services. Assume σ ≈ 9.4 thousand dollars.
54.4 | 54.4 | 27.1 | 38.3 | 53.0 | 48.1 | 48.8 | 42.5 | 42.5 | 33.0 | 33.6 |
36.9 | 27.0 | 47.1 | 33.8 | 28.1 | 28.5 | 29.1 | 36.5 | 36.1 | 26.9 | 27.8 |
28.8 | 29.3 | 31.5 | 31.7 | 31.1 | 38.0 | 32.0 | 31.7 | 32.9 | 23.1 | 54.9 |
43.8 | 36.9 | 31.9 | 25.5 | 23.2 | 29.8 | 22.3 | 26.5 | 26.7 |
thousand dollars
(b) Let us say that the preceding data are representative of the entire sector of (successful) financial services corporations. Find a 75% confidence interval for μ, the average annual profit per employee for all successful banks. (Round your answers to two decimal places.)
lower limit | thousand dollars |
upper limit | thousand dollars |
(c) Let us say that you are the manager of a local bank with a large number of employees. Suppose the annual profits per employee are less than 30 thousand dollars per employee. Do you think this might be somewhat low compared with other successful financial institutions? Explain by referring to the confidence interval you computed in part (b).
(d) Suppose the annual profits are more than 40 thousand dollars per employee. As manager of the bank, would you feel somewhat better? Explain by referring to the confidence interval you computed in part (b).
(e) Find a 90% confidence interval for μ, the average annual profit per employee for all successful banks. (Round your answers to two decimal places.)
lower limit | thousand dollars |
upper limit | thousand dollars |
(f) Let us say that you are the manager of a local bank with a large number of employees. Suppose the annual profits per employee are less than 30 thousand dollars per employee. Do you think this might be somewhat low compared with other successful financial institutions? Explain by referring to the confidence interval you computed in part (e).
(g) Suppose the annual profits are more than 40 thousand dollars per employee. As manager of the bank, would you feel somewhat better? Explain by referring to the confidence interval you computed in part (e).
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