Question

If you are constructing a 95% confidence interval for a normally distributed population when your sample size is 10, what value should you use for tα/2? (round to two decimal places)

Answer 1

This is something you'll need a T table for, or a calculator that can compute critical T values. Either way, we have n = 10 as our sample size, so df = n-1 = 10-1 = 9 is the degrees of freedom.

If you use a table, look at the row that starts with df = 9. Then look at the column that is labeled "95% confidence"

I show an example below of what I mean.

In that diagram, the row and column mentioned intersect at 2.262 (which is approximate). This value then rounds to 2.26

Answer:  2.26