标题: Reading 8: Probability Concepts-LOS b 习题精选 [打印本页]
作者: 1215 时间: 2011-3-1 15:06 标题: [2011]Session 2-Reading 8: Probability Concepts-LOS b 习题精选
Session 2: Quantitative Methods: Basic Concepts
Reading 8: Probability Concepts
LOS b: Explain the two defining properties of probability and distinguish among empirical, subjective, and a priori probabilities.
Which of the following is an a priori probability?
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A) |
For a stock, based on prior patterns of up and down days, the probability of the stock having a down day tomorrow. | |
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B) |
The probability the Fed will lower interest rates prior to the end of the year. | |
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C) |
On a random draw, the probability of choosing a stock of a particular industry from the S& 500. | |
A priori probability is based on formal reasoning and inspection. Given the number of stocks in the airline industry in the S&500 for example, the a priori probability of selecting an airline stock would be that number divided by 500.
作者: 1215 时间: 2011-3-1 15:06
Each lottery ticket discloses the odds of winning. These odds are based on:
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B) |
the best estimate of the Department of Gaming. | |
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An a priori probability is based on formal reasoning rather than on historical results or subjective opinion.
作者: 1215 时间: 2011-3-1 15:07
Last year, the average salary increase for poultry research assistants was 2.5%. Of the 10,000 poultry research assistants, 2,000 received raises in excess of this amount. The odds that a randomly selected poultry research assistant received a salary increase in excess of 2.5% are:
For event “E,” the probability stated as odds is: P(E) / [1 – P(E)]. Here, the probability that a poultry research assistant received a salary increase in excess of 2.5% = 2,000 / 10,000 = 0.20, or 1/5 and the odds are (1/5) / [1 – (1/5)] = 1/4, or 1 to 4.
作者: 1215 时间: 2011-3-1 15:07
Which of the following statements about the defining properties of probability is most accurate?
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A) |
The probability of any event is between 0 and 1, exclusive. | |
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B) |
The sum of the probabilities of events E1 though Ex equals one if the events are mutually exclusive or exhaustive. | |
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C) |
If the device that generates an event is not fair, the events can be mutually exclusive and exhaustive. | |
Even if the device that generates an event is not fair, the events can be mutually exclusive and exhaustive. Consider a standard die with the possible outcomes of 1,2,3,4,5 and 6. The P(2 or 4 or 6) = 0.50 and P(1 or 3 or 5) = 0.50, and thus the probabilities sum to 1 and are mutually exclusive and exhaustive. An unfair die would not change this.
Both remaining statements are false. The probability of any event is between 0 and 1, inclusive. It is possible that the probability of an event could equal 0 or 1, or any point in between. The sum of the probabilities of events E1 though Ex equals 1 if the events are mutually exclusive and exhaustive.
作者: 1215 时间: 2011-3-1 15:07
An empirical probability is one that is:
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A) |
supported by formal reasoning. | |
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B) |
determined by mathematical principles. | |
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C) |
derived from analyzing past data. | |
An empirical probability is one that is derived from analyzing past data. For example, a basketball player has scored at least 22 points in each of the season’s 18 games. Therefore, there is a high probability that he will score 22 points in tonight’s game.
作者: 1215 时间: 2011-3-1 15:07
Which of the following sets of numbers does NOT meet the requirements for a set of probabilities?
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B) |
(0.10, 0.20, 0.30, 0.40). | |
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C) |
(0.10, 0.20, 0.30, 0.40, 0.50). | |
A set of probabilities must sum to one.
作者: 1215 时间: 2011-3-1 15:08
Which of the following is an empirical probability?
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A) |
For a stock, based on prior patterns of up and down days, the probability of the stock having a down day tomorrow. | |
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B) |
The probability the Fed will lower interest rates prior to the end of the year. | |
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C) |
On a random draw, the probability of choosing a stock of a particular industry from the S& 500 based on the number of firms. | |
There are three types of probabilities: a priori, empirical, and subjective. An empirical probability is calculated by analyzing past data.
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