Probability and Statistics > TI 89 for Statistics > TI 89 Binomial Probability

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 BinomCdf will calculate multiple values for X (for example, less or greater than a certain number, or between two x-values). This article covers the BinomCDF function. If you only have one x-value (i.e. X-3 or X=6), see this article on using BinomPdf on the TI-89.

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, otherwise you won’t be able to access the function.

**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 **BinomCdf** 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**: Make sure you’re choosing the right function (BinomCDF or BinomPDF). 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.

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.

Matt,

Check the “Float.” It’s under “Mode” and display digits.

Regards,

Stephanie