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Confidence interval (home costs)

Class Time:

Names:

    Student learning outcomes

  • 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.

  1. Complete the table:
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________
    __________ __________ __________ __________ __________

    Describe the data

  1. Compute the following:
    1. x ¯ = _____
    2. s x = _____
    3. n = _____
  2. In words, define the random variable X ¯ .
  3. State the estimated distribution to use. Use both words and symbols.

    Find the confidence interval

  1. Calculate the confidence interval and the error bound.
    1. Confidence Interval: _____
    2. Error Bound: _____
  2. How much area is in both tails (combined)? α = _____
  3. How much area is in each tail? α 2 = _____
  4. 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.
    Normal distribution curve with two vertical upward lines from the x-axis to the curve. The confidence interval is between these two lines. The residual areas are on either side.
  5. 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

  1. 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.
  2. In one to two complete sentences, explain what this confidence interval means for this particular study.

    Use the data to construct confidence intervals

  1. Using the given information, construct a confidence interval for each confidence level given.
    Confidence level EBM/Error Bound Confidence Interval
    50%
    80%
    95%
    99%
  2. 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?
AMIT Reply
what is chis square
Remelyn Reply
A chi-square (χ2) statistic is a test that measures how a model compares to actual observed data.
kalim
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Sangeetha
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Sangeetha
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Sangeetha
what is the median of the following set of number:3,3,3,4,5,6,7,8,8,9?
Sur Reply
3
Mbemah
5.6
Alekya
(5+6)/2=5.5555.......=5.6
Lyrical
(5+6)/2=5.5 that is the median
moniba
differences between Intervals and Ratio measurement scales
VIP Reply
interval is the distinct from a starting point to the peak of a certain distance
Mbemah
the taking of a certain range accurately in a divisional way
Mbemah
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mukesh
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mukesh
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Sangeetha
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Hemanta
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Abebe
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Sangeetha
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mukhtar
in statistical inferences we use population parameter to infer sample statistics
anupama Reply
Yes
lukman
how do we calculate decile
Drix Reply
how do we calculate class boundaries
Syed
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.
Ekene
complete definition plz
Zarifa Reply
what are the advantages and disadvantages of primary and secondary data
Elisha Reply
the average increase for all NASDAQ stocks is the
Technical Reply
formula of poisson probability distribution
Ch Reply
frequency distribution table
Ali Reply
Giveanswer
Girma
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Babra Reply
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Noman Reply
Statistics is the collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions.
John
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Source:  OpenStax, Introductory statistics. OpenStax CNX. May 06, 2016 Download for free at http://legacy.cnx.org/content/col11562/1.18
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