Statistics How To

TI 83 NormalCDF / TI 84: Easy Step by Step Examples

Probability and Statistics > TI 83 > TI 83 NormalCDF + YI 84

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:

  1. Press the 2nd key.
  2. Press VARS .
  3. Scroll to option 2—or just press “2”— for “normalcdf.”

ti 84 ti 83 normalCDF

Format

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:

Sample 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 2: Enter the following numbers into the screen:
90 for the lower bound, followed by a comma, then 100 for the upper bound, followed by another comma.

Step 3: Press 75 (for the mean), followed by a comma and then 5 (for the standard deviation).

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!

------------------------------------------------------------------------------

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. If you rather get 1:1 study help, Chegg Tutors offers 30 minutes of free tutoring to new users, so you can try them out before committing to a subscription.

If you prefer an online interactive environment to learn R and statistics, this free R Tutorial by Datacamp is a great way to get started. If you're are somewhat comfortable with R and are interested in going deeper into Statistics, try this Statistics with R track.

Comments? Need to post a correction? Please post a comment on our Facebook page.

Check out our updated Privacy policy and Cookie Policy

TI 83 NormalCDF / TI 84: Easy Step by Step Examples was last modified: June 26th, 2018 by Stephanie