Microsoft Office Tutorials and References

In Depth Information

**Using NORM. DIST and POISSON. DIST to Determine Probabilities**

✓
The second argument is the mean of the Poisson distribution to use.

This too must be an integer value greater than 0.

✓
The third argument is TRUE if you want the cumulative probability and

FALSE if you want the noncumulative probability.

Figure 11-11:

A

cumulative Poisson

distribution

with a

mean of 20.

For example, suppose that you’re the manager of a factory that makes brake

shoes. Your district manager has announced an incentive: You’ll receive a

bonus for each day that the number of defective shoes is less than 20. How

many days a month will you meet this goal, knowing that the average number

of defective brake shoes is 25 per day? Here are the steps to follow:

1. In a new worksheet, enter the average number of defects per day (25)

in a cell.

If desired, enter an adjacent label to identify the cell.

2. In the cell below, type
=POISSON.DIST(
to start the function entry.

3. Enter the value
20.

4. Enter a comma (
,).

5. Click the cell where you entered the average defects per day, or enter

its cell address.

6. Enter a comma (
,).

7. Enter
TRUE)
.

8. Press Enter to complete the formula.

9. If desired, enter a label in an adjacent cell to identify this as the

probability of 20 or fewer defects.