<p>I'm on topic 14 in the AP Barron's book, and I'm totally lost . they calculate the t-score of a sample and use that to find some other value (I think the percentile or something), I think I need a chart or something to find that number. the t score is like 2.43. can anyone help please?</p>
<p>sorry if that made NO SENSE whatsoever. I've studied stats for a week or 2 and I am not really sure what I'm doing</p>
<p>you need to know the degrees of freedom in your sample and then you can use either a chart or your caculator to find the P-value that corresponds to a t statistic of 2.43.</p>
<p>right... but if you don't have a chart for df and tscores... go to t-test in the 83 and run the test... it should give you a test statistic from which you can backsolve for the t-score... this needs to be shown for credit to be given on the stat test</p>
<p>so for the free response, I can just tell them, I used my TI-83 and did this and that calculation?</p>
<p>BTW, what is varience? I know how to solve for it(sum of squares of differences b/w mean and data) , but what exactly is it? and I know standard deviation is the square root of the varience. but I don't exaclt know what that is either. I know you can multiply that by a specified Z-score to find the range for a percentile of a sample ( or is it population?) </p>
<p>I'm kinda worried bout this. I make a lot of mistakes in math and my communication skills (especially in math) suck.</p>
<p>you don't need a chart for df. you just do the number of observations minus one for a one sample t test.</p>
<p>I found this</a> chart for you.</p>
<p>Perhaps it would have been wise to start studying earlier if you are so worried about this (and do not know what standard</a> deviation is).</p>
<p>i think they give you a chart on the test... but* no u can't just say the calc did it for you... the calc will give you the margin of error, from which you need to show ur calculations for backsolve to get the t-score</p>