I've been having some trouble with my Stat List Editor application on the TI-89 Titanium (well, more like than just a normal problem). I can't seem to get the correct answer for a statistics problem, no matter what field I put my numbers in (I'm also pretty clueless about SLE in general, since my professor doesn't know how to use an 89, and can't help me in class).
Here's the problem:
Find the z-score for which 5% of the distribution's area lies between -z and z.
For a similar problem (with 80% instead of 5%), I got the right answer by looking at the Critical Values list on my z-score chart. I looked under .80 in the 'level of confidence column,' and then looked to its corresponding zc column, to get 1.28 and -1.28 as my answers. Unfortunately, this list only starts at .80, and only gives the zc for .9, .95, and .99.
Would anyone know to solve the problem above, and others like it, with SLE, by hand, or otherwise?