Answer:
(a) Critical value of t for a 99% confidence interval with df 26 is 2.48.
(b) Critical value of t for a 98% confidence interval with df 58 is 2.07.
Step-by-step explanation:
We are assuming that both critical values are calculated using the one-tailed test.
(a) We are given the 99% confidence interval with degree of freedom 26.
So, for calculating critical values of t, we need level of significance and degree of freedom;
Degree of freedom for t test = 26
Level of significance = 1 - 0.99 = 0.01 or 1%.
Now, in the t table looking for the critical value at v = 26 and P = 0.01 , we get critical value of t as 2.48.
(b) We are given the 98% confidence interval with degree of freedom 58.
So, for calculating critical values of t, we need level of significance and degree of freedom;
Degree of freedom for t test = 58
Level of significance = 1 - 0.98 = 0.02 or 2%.
Now, in the t table the degree of freedom of 58 is not given, so we have to find the required value between degree of freedom 50 and 60 and P between 5% and 2.5% using interpolation method.
Now, in the t table looking for the critical value at v = 58 and P = 0.02 , we get critical value of t as 2.07.