Chapter 8.5, Problem 3E

To determine

To Fill : the blanks of the sentence related to formula of permutation.

Answer to Problem 3E

First blank must be filled with $n$ and second blank must be filled with $r$ .

Explanation of Solution

Given information : Need to fill in the blanks for following statement.

The formula $P{}_r=\frac{n!}{\left(n-r\right)!}$ represents the number of permutation of _________ objects taken _______at a time.

Formula used:

  $P{}_r=\frac{n!}{\left(n-r\right)!}$

where $n=$ total number of objects and $r=$ number of objects selected at a time.

On comparing the given sentence with the formula of permutation, it can be concluded that first blank must be filled with $\underset{\_}{n}$ as it the total number of objects and second blank must be filled with $\underset{\_}{r}$ that is objects taken at a time.