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Ch. 5 - Normal Probability Distributions
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 5.RE.2

In Exercises 1 and 2, use the normal curve to estimate the mean and standard deviation.


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Step 1: Observe the normal curve provided in the image. The curve is symmetric, which indicates that the data follows a normal distribution. The peak of the curve represents the mean (μ), and the spread of the curve is determined by the standard deviation (σ).
Step 2: Identify the mean (μ) from the graph. The mean is located at the center of the curve, which corresponds to the value of 55 on the x-axis.
Step 3: Estimate the standard deviation (σ) using the red dashed lines. These lines mark one standard deviation away from the mean on both sides. From the graph, the values at one standard deviation are approximately 50 and 60.
Step 4: Calculate the standard deviation (σ) by finding the distance between the mean and one of the dashed lines. For example, σ = |55 - 50| = 5 or σ = |60 - 55| = 5.
Step 5: Summarize the findings: The mean (μ) is 55, and the standard deviation (σ) is 5. These values describe the normal distribution represented by the curve.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Normal Distribution

The normal distribution is a continuous probability distribution characterized by its bell-shaped curve, symmetric about the mean. It is defined by two parameters: the mean (average) and the standard deviation (spread). In a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, 95% within two, and 99.7% within three, making it essential for statistical analysis.
추천 영상:
가이드 코스
06:23
Using the Normal Distribution to Approximate Binomial Probabilities

Mean

The mean is the average value of a set of numbers, calculated by summing all values and dividing by the count of values. In the context of a normal distribution, the mean represents the center of the distribution, where the highest point of the curve occurs. It is a measure of central tendency that provides a useful summary of the data set.
추천 영상:
가이드 코스
04:52
Calculating the Mean

Standard Deviation

Standard deviation is a statistic that quantifies the amount of variation or dispersion in a set of values. A low standard deviation indicates that the values tend to be close to the mean, while a high standard deviation indicates a wider spread. In the context of the normal distribution, it helps determine the width of the curve and the proportion of data within specific ranges around the mean.
추천 영상:
가이드 코스
08:45
Calculating Standard Deviation
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교과서 질문

Assume the machine shifts and is filling the vials with a mean amount of 9.96 milligrams and a standard deviation of 0.05 milligram. You select five vials and find the mean amount of compound added.


c. Which is more sensitive to a shift of parameters—an individual random selection or a randomly selected sample mean?

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교과서 질문

In Exercises 5 and 6, find the area of the indicated region under the standard normal curve. If convenient, use technology to find the area.


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교과서 질문

Assume the machine shifts and the distribution of the amount of the compound added now has a mean of 9.96 milligrams and a standard deviation of 0.05 milligram. You select one vial and determine how much of the compound was added.

b. You randomly select 15 vials. What is the probability that you select at least one vial that is within the acceptable range?


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교과서 질문

Assume the machine shifts and is filling the vials with a mean amount of 9.96 milligrams and a standard deviation of 0.05 milligram. You select five vials and find the mean amount of compound added.



b. You randomly select three samples of five vials. What is the probability that you select at least one sample of five vials that has a mean that is within the acceptable range?


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교과서 질문

In Exercises 27–32, the random variable x is normally distributed with mean mu=74 and standard deviation sigma=8. Find the indicated probability.


P(72 < x < 82)

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교과서 질문

In Exercises 7–18, find the indicated area under the standard normal curve. If convenient, use technology to find the area.


To the left of z = -1.95

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