Given that, sample size ( n ) = 18
sample standard deviation ( s ) = 1.5 years
Degrees of freedom = 18 - 1 = 17
confidence level = 0.98
=> significance level = 1 - 0.98 = 0.02
Using Excel we get, chi-square critical values,
The 98% confidence interval for population standard deviation is,
Answer: 98% confidence interval is, (1.07, 2.44) years.
2. The mean replacement time for a random sample of 18 washing machines is $.6 years...
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