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In: Statistics and Probability

A Stat 160 instructor is curious about what the variance is for the grades in his...

A Stat 160 instructor is curious about what the variance is for the grades in his class. He randomly chooses 20 students from his class and ﬁnds the variance of grades is 15.2. Assume that the grades of the class are normally distributed and ﬁnd a 99% conﬁdence interval for the variance of the class’s grades

Expert Solution

The formula for calculating the confidence interval for the population variance is:

In the question, we are asked to find the 99% confidence interval for the population variance of the class's grades, i..e, .

Given: sample size, ; sample variance,

Critical value: For 99% confidence

Calculation of 99% confidence interval-

So we are 99% confident that the population variance of class grades is between and , i.e., the population variance is between

orchestra answered 1 year ago

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