Question

In: Statistics and Probability

Find the 80% confidence interval for the standard deviation of the ages of seniors at Oak...

Find the 80% confidence interval for the standard deviation of the ages of seniors at Oak Park College if a random sample of 21 students has a standard deviation of 2.3 years. Assume the variable is normally distributed.

Solutions

Expert Solution

Solution :

Given that,

s = 2.3

s2 = 5.29

2R = 2/2,df = 28.412

2L = 21 - /2,df = 12.443

The 80% confidence interval for is,

(n - 1)s2 / 2/2 < < (n - 1)s2 / 21 - /2

(20)(5.29) / 28.412 < < (20)(5.29) / 12.443

1.93 < < 2.92

(1.93 ,2.92)


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