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Ch. 2 - Descriptive Statistics
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Non è quello che usi tu?Cambia libro di testo
Capitolo 2, Problema 2.Q.6a

Refer to the sample statistics from Exercise 5 and determine whether any of the house prices below are unusual. Explain your reasoning.


a. \$225,000

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Step 1: Recall the rule for identifying unusual values. A value is considered unusual if it lies more than 2 standard deviations away from the mean. Mathematically, this can be expressed as: \( \text{Unusual if: } x < \mu - 2\sigma \text{ or } x > \mu + 2\sigma \), where \( \mu \) is the mean and \( \sigma \) is the standard deviation.
Step 2: Obtain the mean (\( \mu \)) and standard deviation (\( \sigma \)) of the house prices from the sample statistics provided in Exercise 5. These values are necessary to calculate the range of usual values.
Step 3: Calculate the lower bound of usual values using the formula \( \mu - 2\sigma \). Substitute the mean and standard deviation into the formula to find this value.
Step 4: Calculate the upper bound of usual values using the formula \( \mu + 2\sigma \). Again, substitute the mean and standard deviation into the formula to find this value.
Step 5: Compare the given house price of \$225,000 to the calculated range of usual values. If \$225,000 lies outside the range \( [\mu - 2\sigma, \mu + 2\sigma] \), it is considered unusual. Otherwise, it is not unusual.

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Unusual Values

In statistics, an unusual value, or outlier, is a data point that significantly differs from the other observations in a dataset. Typically, values that lie beyond 1.5 times the interquartile range (IQR) from the quartiles are considered unusual. Identifying unusual values helps in understanding the distribution and variability of the data.
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Step 3: Get P-Value

Descriptive Statistics

Descriptive statistics summarize and describe the main features of a dataset. Key measures include the mean, median, mode, range, variance, and standard deviation. These statistics provide a foundation for understanding the overall trends and patterns in the data, which is essential for determining whether specific values are unusual.
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Parameters vs. Statistics

Normal Distribution

A normal distribution is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean. Understanding the properties of normal distribution, including the empirical rule (68-95-99.7), helps in assessing how likely a particular value is to be considered unusual within the context of the dataset.
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Finding Standard Normal Probabilities using z-Table
Pratica correlata
Domanda del libro di testo

Refer to the sample statistics from Exercise 5 and determine whether any of the house prices below are unusual. Explain your reasoning.


d. \$147,000

144
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Domanda del libro di testo

The data set represents the number of minutes a sample of 27 people exercise each week.

108 139 120 123 120 132 123 131 131

157 150 124 111 101 135 119 116 117

127 128 139 119 118 114 127 142 130


g. Display the data using a box-and-whisker plot.

135
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Domanda del libro di testo

The data set represents the number of minutes a sample of 27 people exercise each week.

108 139 120 123 120 132 123 131 131

157 150 124 111 101 135 119 116 117

127 128 139 119 118 114 127 142 130


a. Construct a frequency distribution for the data set using five classes. Include class limits, midpoints, boundaries, frequencies, relative frequencies, and cumulative frequencies.

150
views
Domanda del libro di testo

The data set represents the number of minutes a sample of 27 people exercise each week.

108 139 120 123 120 132 123 131 131

157 150 124 111 101 135 119 116 117

127 128 139 119 118 114 127 142 130


d. Describe the shape of the distribution as symmetric, uniform, skewed left, skewed right, or none of these.

99
views
Domanda del libro di testo

The data set represents the number of minutes a sample of 27 people exercise each week.

108 139 120 123 120 132 123 131 131

157 150 124 111 101 135 119 116 117

127 128 139 119 118 114 127 142 130

b. Display the data using a frequency histogram and a frequency polygon on the same axes.

33
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Domanda del libro di testo

Weekly salaries (in dollars) for a sample of construction workers are listed.

1100 720 1384 1124 1255 976 718 1316

749 1062 1248 891 969 790 860 1100


a. Find the mean, median, and mode of the salaries. Which best describes a typical salary?

91
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