Plastic sheets produced by a machine are periodically monitored for possible fluctuations in thickness. Typically, a variance in thickness around 1.95 square millimeters is regarded as acceptable. As part of quality control, a random sample of 30 plastic sheets are taken and the sample variance is calculated to be 3.17. Assume that the population is normally distributed. Let a = 0.05. (a) Construct a confidence interval for population variance at (1 − a) confidence level. (b) Test against an upper-tail hypothesis that the true population variance is larger than 1.95.

MATLAB: An Introduction with Applications
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Plastic sheets produced by a machine are periodically monitored for possible
fluctuations in thickness. Typically, a variance in thickness around 1.95 square millimeters
is regarded as acceptable. As part of quality control, a random sample of 30 plastic sheets
are taken and the sample variance is calculated to be 3.17. Assume that the population is
normally distributed. Let a = 0.05.
-
(a) Construct a confidence interval for population variance at (1 − a) confidence level.
(b) Test against an upper-tail hypothesis that the true population variance is larger than
1.95.
Transcribed Image Text:Plastic sheets produced by a machine are periodically monitored for possible fluctuations in thickness. Typically, a variance in thickness around 1.95 square millimeters is regarded as acceptable. As part of quality control, a random sample of 30 plastic sheets are taken and the sample variance is calculated to be 3.17. Assume that the population is normally distributed. Let a = 0.05. - (a) Construct a confidence interval for population variance at (1 − a) confidence level. (b) Test against an upper-tail hypothesis that the true population variance is larger than 1.95.
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