TI 83 NormalCDF / TI 84: Overview
The TI 83 and TI 84 graphing calculators can help you figure out normal distribution probabilities with the normalcdf function.
Normalcdf is the normal (Gaussian) cumulative distribution function on the TI 83/TI 84 calculator. If a random variable is normally distributed, you can use the normalcdf command to find the probability that the variable will fall into a certain interval that you supply.
Where is NormalCDF on the Calculator?
On both the TI 84 and TI 83, NormCDF is in the same place:
- Press the 2nd key.
- Press VARS .
- Scroll to option 2 (or just press “2”) for “normalcdf.”
The format for normalcdf is: normalcdf(lower bound, upper bound, mean, standard deviation). If you have a standard normal distribution (where the mean is 0 and the standard deviation is 1) you can leave the last two variables out, as those are the default settings on the calculator.
TI 83 NormalCDF & TI 84: Steps
Watch the video or read the steps below. Although I’m using a TI 83 here, the TI 84 steps are identical:
Example problem: A group of students taking end of semester statistics exams at a certain college have a mean score of 75 and a standard deviation of 5 points. What is the probability that a given student will score between 90 and 100 points? Use the NormalCDF function.
Step 1: Press the 2nd key and then press VARS then 2 to get “normalcdf.”
Step 4: Close the argument list with a “)”. (Your display should now read normalcdf(90, 100, 75, 5).) Now press ENTER. The calculator returns the probability, which in this case is 0.00135, or .135% (to three decimal places).
That’s how to use the TI 83 NormalCDF function!
Lost your guidebook? Download a new one here from the TI website.
Check out our Youtube channel for more stats help and tips!
Stephanie Glen. "TI 83 NormalCDF / TI 84: Easy Step by Step Examples" From StatisticsHowTo.com: Elementary Statistics for the rest of us! https://www.statisticshowto.com/ti-83-normalcdf/
Need help with a homework or test question? With Chegg Study, you can get step-by-step solutions to your questions from an expert in the field. Your first 30 minutes with a Chegg tutor is free!
Comments? Need to post a correction? Please post a comment on our Facebook page.