Operation Manual

Chapter 13: Inferential Statistics and Distributions 247

normalpdf(

normalpdf( computes the probability density function (pdf) for the normal distribution at a specified x

value. The defaults are mean m=0 and standard deviation s=1. To plot the normal distribution, paste

normalpdf( to the Y= editor. The probability density function (pdf) is:

normalpdf(x[,m,s])

Note: For plotting the normal distribution, you can set window variables Xmin and Xmax so that the

mean m falls between them, and then select 0:ZoomFit from the ZOOM menu.

normalcdf(

normalcdf( computes the normal distribution probability between lowerbound and upperbound for the

specified mean m and standard deviation s. The defaults are m=0 and s=1.

normalcdf(lowerbound,upperbound[,m,s])

invNorm(

invNorm( computes the inverse cumulative normal distribution function for a given area under the

normal distribution curve specified by mean m and standard deviation s. It calculates the x

value

associated with an

area to the left of the x value. 0  area  1 must be true. The defaults are m=0 and

s=1.

invNorm(area[,m,s])

Note: For this example,

Xmin = 28

Xmax = 42

Xscl = 1

Ymin = 0

Ymax = .2

Yscl = .1

fx

2

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

x –

2

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

–

 0,=