Find the t-value such that the area under the t-distribution to the right of the t-value is 0.10, assuming 15 degrees of freedom (df). That is, find t0.10 with 15 degrees of freedom.

Approach

Step 1 Draw a t-distribution with the unknown t-value labeled. Shade the area under the curve to the right of the t-value, as in Figure 12.
Step 2 Find the row in Table VII corresponding to 15 degrees of freedom and the column corresponding to an area in the right tail of 0.10. Identify where the row and column intersect. This is the unknown t-value.

Figure 12 ta -Area = a