##### Asked by: Abderrazzak Cajaraville

asked in category: General Last Updated: 25th May, 2020# How do you know when to use invNorm or Normalcdf?

**use normalcdf**when you want to look for a probability, and you

**use invnorm**when you're looking for a value associated with a probability.

Hereof, what is invNorm used for?

The **InvNorm** function (Inverse Normal Probability Distribution Function) on the TI-83 gives you an x-value if you input the area (probability region) to the left of the x-value. The area must be between 0 and 1. You must also input the mean and standard deviation.

Also, how do you use normal CDF? **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.

Keeping this in consideration, what is the difference between Normalpdf and Normalcdf?

**Normalpdf** finds the probability of getting a value at a single point on a normal curve given any mean and standard deviation. **Normalcdf** just finds the probability of getting a value **in a** range of values on a normal curve given any mean and standard deviation.

How do you find the probability distribution?

**How to find the mean of the probability distribution: Steps**

- Step 1: Convert all the percentages to decimal probabilities. For example:
- Step 2: Construct a probability distribution table.
- Step 3: Multiply the values in each column.
- Step 4: Add the results from step 3 together.