Elementary Statistics: A Step By Step Approach
10th Edition
ISBN: 9781259755330
Author: Allan G. Bluman
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 7.4, Problem 1AC
Ages of Presidents at the Time of Their Deaths
Shown are the ages (in years) of the Presidents at the times of their deaths.
1. Do the data represent a population or a sample?
2. Select a random sample of 12 ages and find the variance and standard deviation.
3. Find the 95% confidence interval of the standard deviation.
4. Find the standard deviation of all the data values.
5. Does the confidence interval calculated in question 3 contain the standard deviation?
6. If it does not, give a reason why.
7. What assumption(s) must be considered for constructing the confidence interval in step 3?
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In order to find probability, you can use this formula in Microsoft Excel:
The best way to understand and solve these problems is by first drawing a bell curve and marking key points such as x, the mean, and the areas of interest. Once marked on the bell curve, figure out what calculations are needed to find the area of interest.
=NORM.DIST(x, Mean, Standard Dev., TRUE).
When the question mentions “greater than” you may have to subtract your answer from 1.
When the question mentions “between (two values)”, you need to do separate calculation for both values and then subtract their results to get the answer.
1.
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In the first step, use the above formula and x = 44, calculate probability value.
In the second step repeat the first step with the only difference that x=55.
In the third step, subtract the answer of the first part from the…
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In New York State, the mean salary for high school teachers in 2022 was 81,410 with a standard deviation of 9,500. Only Alaska’s mean salary was higher. Assume New York’s state salaries follow a normal distribution.
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Chapter 7 Solutions
Elementary Statistics: A Step By Step Approach
Ch. 7.1 - What is the difference between a point estimate...Ch. 7.1 - What information is necessary to calculate a...Ch. 7.1 - What is the margin of error?Ch. 7.1 - What is meant by the 95% confidence interval of...Ch. 7.1 - What are three properties of a good estimator?Ch. 7.1 - What statistic best estimates ?Ch. 7.1 - Find each. a. z/2 for the 99% confidence interval...Ch. 7.1 - What is necessary to determine the sample size?Ch. 7.1 - Fuel Efficiency of Cars and Trucks Since 1975 the...Ch. 7.1 - Fast-Food Bills for Drive-Thru Customers A random...
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Prob. 9ECh. 7.4 - Stock Prices A random sample of stock prices per...Ch. 7.4 - Cost of an Operation A medical researcher surveyed...Ch. 7.4 - Home Ownership Rates The percentage rates of home...Ch. 7.4 - Calories in a Standard Size Candy Bar Estimate the...Ch. 7.4 - SAT Scores Estimate the variance in mean...Ch. 7.4 - Daily Cholesterol Intake The American Heart...Ch. 7.4 - Calculator Battery Lifetimes A confidence interval...Ch. 7 - Eye Blinks A survey of 49 individuals found that...Ch. 7 - Vacation Days A U.S. Travel Data Center survey...Ch. 7 - Blood Pressure A researcher wishes to estimate...Ch. 7 - Shopping Survey A random sample of 49 shoppers...Ch. 7 - Lengths of Childrens Animated Films The lengths...Ch. 7 - Dog Bites to Postal Workers For a certain urban...Ch. 7 - Number of Credit Cards In a recent survey of 1000...Ch. 7 - Vacation Sites A U.S. Travel Data Centers survey...Ch. 7 - Prob. 7.3.9RECh. 7 - Adult Educational Activities A local county has a...Ch. 7 - Prob. 7.3.11RECh. 7 - 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