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Ch. 5 - Discrete Probability Distributions
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 5.1.7

Identifying Probability Distributions. In Exercises 7–14, determine whether a probability distribution is given. If a probability distribution is given, find its mean and standard deviation. If a probability distribution is not given, identify the requirements that are not satisfied.
Plane Crashes The table lists causes of fatal plane crashes with their corresponding probabilities.
Table of plane crash causes with probabilities: Pilot Error 0.58, Mechanical 0.17, Weather 0.06, Sabotage 0.09, Other 0.10.

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Step 1: Verify if the given data represents a probability distribution. To do this, check two key requirements: (a) All probabilities must be between 0 and 1, and (b) The sum of all probabilities must equal 1.
Step 2: Add the probabilities provided in the table: Pilot Error (0.58), Mechanical (0.17), Weather (0.06), Sabotage (0.09), and Other (0.10). Use the formula: \( \text{Sum} = P_1 + P_2 + P_3 + P_4 + P_5 \).
Step 3: If the sum of probabilities equals 1 and all probabilities are between 0 and 1, confirm that the data represents a probability distribution. If not, identify which requirement is violated.
Step 4: To find the mean of the probability distribution, use the formula \( \mu = \sum (x \cdot P(x)) \), where \( x \) represents the causes (numerical values assigned to each category) and \( P(x) \) represents the probabilities.
Step 5: To find the standard deviation, use the formula \( \sigma = \sqrt{\sum (x^2 \cdot P(x)) - \mu^2} \). Calculate \( \sum (x^2 \cdot P(x)) \), subtract \( \mu^2 \), and take the square root of the result.

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주요 개념

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Probability Distribution

A probability distribution is a mathematical function that provides the probabilities of occurrence of different possible outcomes in an experiment. For a set of outcomes to qualify as a probability distribution, the sum of all probabilities must equal 1, and each individual probability must be between 0 and 1. In the context of the plane crash causes, we need to verify if these conditions are met.
추천 영상:
가이드 코스
06:39
Calculating Probabilities in a Binomial Distribution

Mean of a Probability Distribution

The mean of a probability distribution, also known as the expected value, is a measure of the central tendency of the distribution. It is calculated by multiplying each outcome by its probability and summing these products. In this case, if the distribution is valid, we would compute the mean to understand the average cause of plane crashes based on the given probabilities.
추천 영상:
가이드 코스
03:28
Mean & Standard Deviation of Binomial Distribution

Standard Deviation of a Probability Distribution

The standard deviation of a probability distribution quantifies the amount of variation or dispersion of the outcomes. It is calculated by taking the square root of the variance, which is the average of the squared differences from the mean. Understanding the standard deviation helps assess the reliability of the probabilities associated with the causes of plane crashes.
추천 영상:
가이드 코스
08:45
Calculating Standard Deviation
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교과서 질문

Notation Assume that we want to find the probability that when five speaking characters in movies are randomly selected, exactly two of them are females. Also assume that when randomly selecting a speaking character in a movie, the probability of getting a female is 0.331. Identify the values of n, x, p, and q.

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교과서 질문

Significant For 100 births, P(exactly 56 girls) and P(56 or more girls) Is 56 girls in 100 births a significantly high number of girls? Which probability is relevant to answering that question?

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교과서 질문

Identifying Probability Distributions. In Exercises 7–14, determine whether a probability distribution is given. If a probability distribution is given, find its mean and standard deviation. If a probability distribution is not given, identify the requirements that are not satisfied.

Fear of Heights The table lists results from a survey of 285 subjects who were asked, “Are you afraid of heights in tall buildings?” The results are from USA Today.

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교과서 질문

Independent Events Again assume that when randomly selecting a speaking character in a movie, the probability of getting a female is 0.331, as in Exercise 1. If we want to find the probability of 20 females when 50 different speaking characters are randomly selected from a population of 1500 speaking characters, are the 50 selections independent? Using the 5% guideline for cumbersome calculations, can they be treated as being independent?

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교과서 질문

Biometric Security In a USA Today survey of 510 people, 270 (or 53%) said that we should replace passwords with biometric security, such as fingerprints. Use the following probabilities related to determining whether the result of 270 is significantly high (assuming the true rate is 50%). Is 270 significantly high? What should be concluded about the claim that the majority of the population says that we should replace passwords with biometric security? Explain.


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교과서 질문

Planets The planets of the solar system have the numbers of moons listed below in order from the sun. (Pluto is not included because it was uninvited from the solar system party in 2006.) Include appropriate units whenever relevant.


0 0 1 2 17 28 21 8


i. What is the level of measurement of the data: nominal, ordinal, interval, or ratio?

j. Are the data discrete or continuous?

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