a.
To check: If the conditions of normality are satisfied or not.
a.
Answer to Problem 12PT
Yes.
Explanation of Solution
Given:
Sample mean = 6.208
Sample standard deviation = 2.576
Formula used:
The formula to compute the confidence interval is:
To construct the confidence interval either the sample size should be 30 or more or the population must be distributed normal.
Here, sample size is above 30. Thus, it could be concluded that the normality assumption is met.
b.
To find: The mistake in the confidence interval of Maurice and compute the 95% confidence interval.
b.
Answer to Problem 12PT
The confidence interval is (5.4565, 6.9594).
Explanation of Solution
Calculation:
Maurice has computed z-interval instead of t-interval and also, he has taken incorrect standard deviation.
The degree of freedom is 48-1 = 47
From the t-table, the critical value at 95% confidence level is 2.021.
The 95% confidence interval could be computed as:
Thus, the confidence interval is (5.4565, 6.9594).
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