Quiz confidence interval for population mean

Question

Find the critical value tα2 needed to construct a confidence interval of the given level with the given sample size. Round the answer to at least three decimal places.

Level 95% sample size 21



Critical value= ?

Answer 1

Your critical value of t_α/2 can be found in a t score table. You will have degrees of freedom (df) equal to n-1 or 20. Then, since α = 1-.95 = .05, look for the column with 5% in two tails or 2.5% in one tail and 20 d.f. You should find 2.086.

Alternatively if you're using a calculator, you will find it to be 2.085963.