Statistics How To

T distribution on a TI 83: How to Find it in Easy Steps

TI 83 calculator for statistics > T distribution on a TI 83

T distribution on a TI 83: Overview

The T distribution (sometimes called Student’s T distribution) is actually a set of distributions, differentiated by the degrees of freedom (df). There’s only a slight difference between the t distribution and a normal curve; In general you use a normal distribution whenever you can. But in some situations (like a very small sample), you have to use the t-distribution to find probabilities.
Take a look at a traditional textbook T table, and you’ll actually find many T tables, which can be a little overwhelming. Instead of poring over tables, you can use a TI 83 graphing calculator to assist you in finding T distribution values.
t distribution on a ti-83
You might be asked to find the area under a T curve, or (like Z scores), you might be given a certain area and asked to find the T score.

T distribution on a TI 83: Steps

Sample problem: Find the area under a T curve with degrees of freedom 10 for P( 1 ≤ X ≤ 2 ). Use the t distribution on a TI 83.

Step 1: Press 2nd VARS 5 to select tcdf(.

Step 2: Enter the lower and upper bounds, and the degrees of freedom. The lower bound is the lowest number and the upper bound is the highest number: 1 , 2 , 1 0 )

Your screen should now read tcdf(1,2,10)

Step 3: Press ENTER. The answer is .133752549, or about 13.38%.

That’s how to find a T distribution on a TI 83!

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