Normal Distribution

There are three styles for computing probability for a normal distribution are shown in the table.

$\begin{array}{l|c|c} &\mathrm{Starting}& \mathrm{Ending}\\ \mathrm{Calculate}& \mathrm{Value}& \mathrm{Value}\\ ------&-----&----\\ P(X < a) & -1E99 & a\\ P(X > a) & a & 1E99\\ P(a < X < b) & a & b\\ \end{array}$

Note: In a normal distribution, it doesn't matter if the question is $<$ or $\leq$ .

The E is scientific notation and is found by pressing

The syntax of the command is: normalcdf(starting value, ending value, mean, standard deviation)

Example: Let X be a continuous random variable with mean 50 and standard deviation 8.

Compute P(42 < X < 52).

Press
Choose 2:normalcdf(
- Note: The normalpdf command will only find the y-values of a normal curve. It will not compute probability.

Press
Press The screen will look like this.

Compute P( X > 52).

Press
Choose 2:normalcdf(
- Note: The normalpdf command will only find the y-values of a normal curve. It will not compute probability.
Press
Press The screen will look like this.