How to use the ttable to find righttail probabilities and pvalues for hypothesis tests involving t:
 First, find the tvalue for which you want the righttail probability (call it t), and find the sample size (for example, n).
 Next, find the row corresponding to the degrees of freedom (df) for your problem (for example, n – 1). Go across that row to find the two tvalues between which your t falls. For example, if your t is 1.60 and your n is 7, you look in the row for df = 7 – 1 = 6. Across that row you find your t lies between tvalues 1.44 and 1.94.
 Then, go to the top of the columns containing the two tvalues from Step 2. The righttail (greaterthan) probability for your tvalue is somewhere between the two values at the top of these columns. For example, your t = 1.60 is between tvalues 1.44 and 1.94 (df = 6); so the right tail probability for your t is between 0.10 (column heading for t = 1.44); and 0.05 (column heading for t = 1.94).
The row near the bottom with Z in the df column gives righttail (greaterthan) probabilities from the Zdistribution.
Use the t table to find t*values (critical values) for a confidence interval involving t:
 Determine the confidence level you need (as a percentage).
 Determine the sample size (for example, n).
 Look at the bottom row of the table where the percentages are shown. Find your % confidence level there.
 Intersect this column with the row representing your degrees of freedom (df).
Practice solving problems using the ttable sample questions below

For a study involving one population and a sample size of 18 (assuming you have a tdistribution), what row of the ttable will you use to find the righttail (“greater than”) probability affiliated with the study results?
Answer: df = 17
The study involving one population and a sample size of 18 has n – 1 = 18 – 1 = 17 degrees of freedom.

For a study involving a paired design with a total of 44 observations, with the results assuming a tdistribution, what row of the table will you use to find the probability affiliated with the study results?
Answer: df = 21
A matchedpairs design with 44 total observations has 22 pairs. The degrees of freedom is one less than the number of pairs: n – 1 = 22 – 1 = 21.

A tvalue of 2.35, from a tdistribution with 14 degrees of freedom, has an uppertail (“greater than”) probability between which two values on the ttable?
Answer: 0.025 and 0.01
Using the ttable, locate the row with 14 degrees of freedom and look for 2.35. However, this exact value doesn’t lie in this row, so look for the values on either side of it: 2.14479 and 2.62449. The uppertail probabilities appear in the column headings; the column heading for 2.14479 is 0.025, and the column heading for 2.62449 is 0.01.
Hence, the uppertail probability for a tvalue of 2.35 must lie between 0.025 and 0.01.