These are real basic "find the t-value from the chart" kinds of problems, such as "Determine percentile

with df = 12," or "Use Table 4 to determine

with df = 19." The problem is, the table only has five columns for right-tail areas of .1, .05, .025, .01, and .005. So I see that Excel is giving me the reverse of what I'm expecting - if I plug in 3.078, 1, 1, the output is close to .1, which is the heading of the corresponding column. So to get what I want in Excel, do I need to use the =TINV formula?