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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

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Problem 4Multiple Choice

A retail analyst recorded service times (minutes) for customers at two checkout configurations: an express lane (for up to 1010 items) and a standard lane (no item limit). From simple random samples, the times are:


Express lane times:
2.1,1.8,2.4,2.0,1.9,2.2,2.3,1.7,2.5,2.02.1,1.8,2.4,2.0,1.9,2.2,2.3,1.7,2.5,2.0
(n1=10)\(\left\)(n_1=10\(\right\))


Standard lane times:
3.0,3.5,2.8,3.2,3.1,2.9,3.4,3.3,2.7,3.03.0,3.5,2.8,3.2,3.1,2.9,3.4,3.3,2.7,3.0
(n2=10)\(\left\)(n_2=10\(\right\))


i. Construct separate 95%95\% confidence intervals for the population standard deviation in each lane.
ii. Based on these intervals, does the express lane appear to have less variability than the standard lane?
iii. Do both samples satisfy the requirements for constructing these intervals?