The student will calculate the 90% confidence interval for the mean cost of a home in the area in which this school is located.
The student will interpret confidence intervals.
The student will determine the effects of changing conditions on the confidence interval.
Collect the data
Check the Real Estate section in your local newspaper. Record the sale prices for 35 randomly selected homes recently listed in the county.
Note
Many newspapers list them only one day per week. Also, we will assume that homes come up for sale randomly.
Complete the table:
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Describe the data
Compute the following:
$\overline{x}$ = _____
${s}_{x}$ = _____
n = _____
In words, define the random variable
$\overline{X}$ .
State the estimated distribution to use. Use both words and symbols.
Find the confidence interval
Calculate the confidence interval and the error bound.
Confidence Interval: _____
Error Bound: _____
How much area is in both tails (combined)?
α = _____
How much area is in each tail?
$\frac{\alpha}{2}$ = _____
Fill in the blanks on the graph with the area in each section. Then, fill in the number
line with the upper and lower limits of the confidence interval and the sample mean.
Some students think that a 90% confidence interval contains 90% of the data. Use the list of data on the first page and count how many of the data values lie within the confidence interval. What percent is this? Is this percent close to 90%? Explain why this percent should or should not be close to 90%.
Describe the confidence interval
In two to three complete sentences, explain what a confidence interval means (in general), as if you were talking to someone who has not taken statistics.
In one to two complete sentences, explain what this confidence interval means for this particular study.
Use the data to construct confidence intervals
Using the given information, construct a confidence interval for each confidence level given.
Confidence level
EBM/Error Bound
Confidence Interval
50%
80%
95%
99%
What happens to the EBM as the confidence level increases? Does the width of the confidence interval increase or decrease? Explain why this happens.
Questions & Answers
the mean of random variable following binomial distribution is 10. the numbers of trails are 30. What the approximate value of variance?
The lower class boundary is found by subtracting 0.5 units from the lowerclass limit and the upper class boundary is found by adding 0.5 units to the upper class limit. The difference between the upper and lowerboundaries of any class.
Ekene
The lower class boundary is found by subtracting 0.5 units from the lowerclass limit and the upper class boundary is found by adding 0.5 units to the upper class limit. The difference between the upper and lowerboundaries of any class.
Statistics is the collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions.