## How to Find Binomial Probability on the TI 83 (BinomPDF)

The TI-83 and higher calculators are equipped with two functions: BinomPDF and BinomCDF to help you make light work of figuring our binomial probabilities. While figuring out binomial distributions by hand can involve multiple equations and lots of time (especially if you are working with cumulative probabilities), entering a binomial probability into the TI 83 is no harder and entering an addition problem into the home screen. This article tells you how to use the BinomPDF function to figure out an exact quantity (like three times, or twice, or a dozen occurrences). For cumulative probabilities (like “up to a certain number” or “between 5 and 10″ or “under 6″ or something similar, you’ll want to check out this other article on TI 83 BinomCDF.

Sample problem: Sue has a batting average of .270. If she is at bat three times, what is the probability that she gets exactly two hits?

Step 1: Press to get the “DISTR” option. Press for “binomPDF.”

Step 2: Enter the number of trials from the question. Sue bats three times, so the number of trials is 3. Press and hit the key.

Step 3: Enter the Probability of Success, P. Sue’s batting average is .240, so enter .270, then hit the key.

Step 4: Enter the X value. We want to know Sue’s chances of getting exactly two hits, so enter and then press .

Step 5: Press for the result. Sue’s chances of getting exactly two hits is .159651.

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.