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.