Microsoft Office Tutorials and References

In Depth Information

**PERMUT**

PERMUT

PERMUT
returns the number of permutations for a given number of objects that can be

selected from a range of numbers.

=PERMUT(number,number_chosen)

Permutations are not the same as combinations. With a combination, the numbers 1 2 3 is the

same as 3 2 1, 1 3 2, 2 3 1, and so on; permutations sees each of these as distinct outcomes.

For example, the
PERMUT
function will tell you how many different ways these numbers can

appear if you select 3 numbers from 1 to 3. Figure 11.36 shows the result.

Is the number of objects in the range.

NUMBER

Is the number of objects in each permutation.

NUMBER_CHOSEN

Figure 11.36

With the
PERMUT

function, each number

selected must be

unique. It accounts for

1 2 3, but not 1 1 1

or 1 1 2.

POISSON

POISSON
returns the Poisson distribution.

=POISSON(x,mean,cumulative)

The Poisson probability distribution is applied to experiments with random and independent

occurrences. The occurrences are always considered within an inter val (time, space, or volume).

Using a known average number of occurrences for the inter val, the
POISSON
function computes

the probability of a certain number of occurrences at the x inter val. Figure 11.37 shows the

Poisson probability distribution for the number of people arriving at a bank branch within a one

hour time period.

Is the number of occurrences within the inter val.

X

Is the average and, therefore, expected number of occurrences.

MEAN

Is a TRUE/FALSE value that determines the form in which the Poisson

probability distribution will be returned. If TRUE, the cumulative

probability is returned (the probability that the number of occurrences will

CUMULATIVE