8. Sampling Distributions & Confidence Intervals: Proportion
Confidence Intervals for Population Variance
8. Sampling Distributions & Confidence Intervals: Proportion
Confidence Intervals for Population Variance: Videos & Practice Problems
1
concept
Constructing Confidence Intervals for Variance or Standard Deviation
Video duration:
6m Study Smarter with Worksheets.
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2
Problem
What is wrong with expressing the confidence interval as ?
A
5.1 is not the midpoint between 3.8 and 6.4.
B
The values 3.8 and 6.4 are impossible because variance must be less than 3.
C
The point estimate for σ2 is not the midpoint of a confidence interval and 1.3 is not a margin of error since the distribution is asymmetric.
D
Confidence intervals can only be written for means or proportion, not for variance.
3
Problem
A delivery service tracks the weights of its packages. A sample of 20 packages has a variance of 4.5 lbs2. Construct a 95% conf. int. for the population variance. Assume a normal distribution.
A
(2.60, 9.60)
B
(2.74, 9.60)
C
(2.99, 8.89)
D
(2.84, 8.45)
4
example
Constructing Confidence Intervals for Variance or Standard Deviation Example 1
Video duration:
5m5
example
Constructing Confidence Intervals for Variance or Standard Deviation Example 2
Video duration:
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