Concept explainers
The waking times (in minutes past 5:00 A.M.) of 40 people who start work at 8:00 A.M. are shown in the table at the left. Assume the population standard deviation is 45 minutes. Find (a) the point estimate of the population
(a)
To find: The point estimate for the mean
Answer to Problem 6.1.1RE
The point estimate for the mean
Explanation of Solution
Given info:
The data shows that the waking times of 40 people who start work at 8:00 A.M.
Calculation:
Point estimate:
The point estimate of the population mean
Software Procedure:
Step by step procedure to obtain the sample mean using the MINITAB software:
- Choose Stat > Basic Statistics > Display Descriptive Statistics.
- In Variables enter the columns Waking times (in minutes past 5).
- In Statistics choose mean.
- Click OK.
Output using the MINITAB software is given below:
From the MINITAB output, the point estimate for the mean waking time is 103.5 minutes.
(b)
To find: The margin of error.
Answer to Problem 6.1.1RE
The margin of error is 11.70.
Explanation of Solution
Given info:
Calculation:
Critical value:
Software procedure:
Step by step procedure to obtain the P-value using the MINITAB software:
- Choose Graph > Probability Distribution Plot choose View Probability > OK.
- From Distribution, choose ‘Normal’ distribution.
- Click the Shaded Area tab.
- Choose Probability Value and Both Tail for the region of the curve to shade.
- Enter the Probability value as 0.10.
- Click OK.
Output using the MINITAB software is given below:
From the output, the critical value
Margin of error:
The formula for the margin of error is,
Substitute 1.645 for
Thus, the margin of error is 11.70.
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Chapter 6 Solutions
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