The **TI-89 Titanium graphing calculator** is a powerful, hand held calculator that can plot graphs, make bar charts, and calculate just about anything related to probability and statistics. It’s possible to calculate binomial probabilities by hand, the TI-89 graphing calculator will save you about thirty minutes of working out. Once you’ve got the hang of entering the binomial **probability numbers** into the **TI-89**, you’ll wonder how you ever did without it.

Sample problem: John’s batting average is .240. If he’s at bat three times, what is the probability that he gets exactly three hits?

**Step 1:** Press Apps and scroll (using the scrolling arrows) to choose **Stats/List Editor**. Press Enter.

**Step 2:** Press F5. Scroll down to **B: Binomial Pdf**. Press Enter.

**Step 3:** Enter the number of trials. John bats three times, so the number of trials is **3**. Press 3 and hit the down arrow key.

**Step 4:** Enter the Probability of Success, **P**. John’s batting average is **.240**, so enter .240. hit the down arrow key.

**Step 5:** Enter the X value. We want to know the probability of John getting exactly three hits, so enter 3 in the X Value box.

**Step 6:** Press Enter for the result. The probability of John getting exactly three hits is **.013824**, returned at the top of the screen as “**Pdf=.013824**“.

**Tip #1**: Instead of scrolling down to Binomial Pdf, you can hit the Alpha and ( keys to select it instead.

**Warning**: BinomialPdf is an exact probability for one value of x. If you want to find a cumulative probability (for example, what are John’s chances of getting 0 or 1 hits?) you will need the use the BinomialCdf function. See: What is the difference between BinomPDF and BinomCDF?

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