Question

Find the critical t-value that corresponds to 98% confidence. Assume 26 degrees of freedom. (Round to 3 decimal places as needed.)

Answer 1

Given

Confidence level = 98%

Degrees of freedom = 26

A T critical value is a “cut off point” on the t distribution.

To help you find critical values for the t-distribution, look up your confidence level in the bottom row of the table; this tells you which column of the t-table you need. Intersect this column with the row for your df (degrees of freedom). The number you see is the critical value (or the t*-value) for your confidence interval.

For the given problem, you want a t*-value for a 98% confidence interval when you have 26 degrees of freedom, so go to the bottom of the table, find the column for 98%, and intersect it with the row for df = 26.

This gives you a t*–value of 2.479

Therefore, the critical t-value that corresponds to 98% confidence with 26 degrees of freedom is 2.479

Or another way of finding critical t-value is as follows:

Level of significance () = 1- 0.98 = 0.02

Look up the df = 26 in the left hand side of the t-distribution table and the = 0.02 along the top row. The intersection of the row and column gives you a t*–value of 2.479