Data Analysis with Microsoft Excel: Updated for Office 2007

Chapter 5 Probability Distributions 187

The probability associated with a range of values is equal to the area un-

der the PDF curve. Note that unlike discrete distributions, we can’t assign a

probability to a specifi c value in a continuous distribution. The probability

of any specifi c value is zero because its area under the curve is zero (it has

a positive height, but zero width). The total area under any PDF curve must

be equal to 1 because the total probability must be 1.

CONCEPT TUTORIALS

PDFs

To see the relationship between probability and the area under the PDF

curve, open the instructional workbook named Probability.

To open the Probability workbook:

1 Open the fi le Probability, located in the Explore folder.

The workbook opens to the Contents page, describing the nature of

the workbook.

2 You can move through the sheets in the workbook, reviewing the

material on probability discussed so far in this chapter.

3 Click Explore a PDF from the Table of Contents column.

The sheet displays the curve shown in Figure 5-4.

Figure 5-3
A sample
probability
density
function