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Ch. 5 - Normal Probability Distributions
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 5, Problem 5.4.6

True or False? In Exercises 5–8, determine whether the statement is true or false. If it is false, rewrite it as a true statement.


As the sample size increases, the standard deviation of the distribution of sample means increases.

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Understand the concept of the standard deviation of the distribution of sample means, also known as the standard error. It is calculated as the population standard deviation divided by the square root of the sample size: σmean = σ / n, where σ is the population standard deviation and n is the sample size.
Analyze the relationship between the sample size (n) and the standard error. As n increases, the denominator of the formula n increases, which causes the standard error to decrease.
Evaluate the given statement: 'As the sample size increases, the standard deviation of the distribution of sample means increases.' Based on the formula and the relationship, this statement is false because the standard error actually decreases as the sample size increases.
Rewrite the statement to make it true: 'As the sample size increases, the standard deviation of the distribution of sample means decreases.'
Conclude that the correct understanding of the relationship between sample size and the standard error is essential for interpreting the behavior of sampling distributions.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Standard Deviation

Standard deviation is a measure of the amount of variation or dispersion in a set of values. In statistics, it quantifies how much individual data points differ from the mean of the dataset. A smaller standard deviation indicates that the data points tend to be close to the mean, while a larger standard deviation indicates more spread out values.
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Central Limit Theorem

The Central Limit Theorem states that, as the sample size increases, the distribution of the sample means will approach a normal distribution, regardless of the shape of the population distribution. This theorem is fundamental in statistics because it allows for the use of normal probability techniques for inference, even when the original data is not normally distributed.
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Distribution of Sample Means

The distribution of sample means, also known as the sampling distribution, is the probability distribution of all possible sample means from a population. As the sample size increases, the standard deviation of this distribution, known as the standard error, decreases, leading to more precise estimates of the population mean. This concept is crucial for understanding how sample size affects statistical inference.
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Related Practice
Textbook Question

Finding Area

In Exercises 23–36, find the indicated area under the standard normal curve. If convenient, use technology to find the area.


To the left of z=1.365

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Textbook Question

Finding a z-Score Given an Area In Exercises 23–30, find the indicated z-score.


Find the z-score that has 78.5% of the distribution’s area to its left.

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Textbook Question

Bags of Baby Carrots The weights of bags of baby carrots are normally distributed, with a mean of 32 ounces and a standard deviation of 0.36 ounce. Bags in the upper 4.5% are too heavy and must be repackaged. What is the most a bag of baby carrots can weigh and not need to be repackaged?

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Textbook Question

Finding Probability In Exercises 47–56, find the indicated probability using the standard normal distribution. If convenient, use technology to find the probability.


P(z < - 1.11)

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Textbook Question

Interpreting the Central Limit Theorem In Exercises 19–26, find the mean and standard deviation of the indicated sampling distribution of sample means. Then sketch a graph of the sampling distribution.


Renewable Energy The zloty is the official currency of Poland. During a recent period of two years, the day-ahead prices for renewable energy in Poland (in zlotys per mega-watt hour) have a mean of 158.51 and a standard deviation of 33.424. Random samples of size 100 are drawn from this population, and the mean of each sample is determined. (Adapted from Multidisciplinary Digital Publishing Institute)

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Textbook Question

Conservation About 74% of the residents in a town say that they are making an effort to conserve water or electricity. One hundred ten residents are randomly selected. What is the probability that the sample proportion making an effort to conserve water or electricity is greater than 80%? Interpret your result.

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