Statistics How To

How to use the TI 89 Binomial Probability Function

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TI 89 Binomial Probability Function
The TI-89 calculator can help you make graphs and charts, calculate probabilities, and perform a wide array of statistics calculations. There are two options for TI 89 binomial probability; The BinomialCdf will calculate multiple values for X (for example, less or greater than a certain number, or between two x-values). If you only have one x-value, see this article on using BinomPdf on the TI-89 for one value. Not sure of the difference between PDF and CDF? See: What is the difference between BinomPDF and BinomCDF?

TI 89 Binomial Probability: Steps

Watch the video or read the steps below:

Note: Make sure you have the Stats/List editor installed.

Sample problem: Jane’s batting average is .230. If she’s at bat four times, what is the probability that she gets three or four hits?
Step 1: Press APPS and use the scroll arrows to highlight the Stats/List Editor. Press ENTER.

Step 2: Press F5. Press ALPHA and ). This should bring up the Binomial Cdf screen. If it doesn’t, make sure you pressed down the ALPHA key (you are using it to choose “C” above the “)” key).

Step 3: Enter the number of trials in the Num Trials box. Jane goes to bat four times, so the number of trials is 4. Press 4 and then the down arrow key.

Step 4: Enter the probability: “Prob Success, p.” Jane’s batting average is .230, so enter .230 in this box. Press the down arrow key.

Step 5: Enter the lower value, 3. You want to know the probability of Jane getting between three and four hits, so you enter 3 in the X Value box.

Step 6: Enter the upper value, 4.

Step 7: Press ENTER twice for the result. The probability of Jane getting three or four hits is .040273, returned at the top of the screen as “Pdf=.040273“.

Tip: Instead hitting the Alpha and ) keys to select BinomialCdf, you can scroll down the menu with the arrow keys instead.

Warning: Use the BinomialPdf function (option B from the F5 menu) if you only have one x-value.

Lost your guidebook? You can download a new one from the TI website here.

2 thoughts on “How to use the TI 89 Binomial Probability Function

  1. Matt

    Hey, Thank you so much for putting this up. It helped me alot since I have a 89 and my teacher uses a 84 so I always have to look how to do the work on mine.

    The only problem I get is that when I do the same problem you did it comes up =.04, do you have any idea why my calculator is rounding?

    Thank you.