Chapter 9, Problem 14CT

(a)

To determine

To find: the value of the given expression.

Answer to Problem 14CT

  $p{}_2=72$

Explanation of Solution

Given information:

Consider $p{}_2$

Formula used:

  $p{}_r=\frac{n!}{(n-r)!}$

Calculation:

Evaluate $p{}_2$

  $\begin{array}{l}p{}_2=\frac{9!}{(9-2)!}\\ =\frac{9\times 8\times 7!}{7!}\\ =72\end{array}$

Hence, $p{}_2=72$

(b)

To determine

To find: the value of the given expression.

Answer to Problem 14CT

  $p{}_3=328,440$

Explanation of Solution

Given information:

Consider $p{}_3$

Formula used:

  $p{}_r=\frac{n!}{(n-r)!}$

Calculation:

Evaluate $p{}_3$

  $\begin{array}{l}p{}_3=\frac{70!}{(70-3)!}\\ =\frac{70\times 69\times 68\times 67!}{67!}\\ =70\times 69\times 68\\ =328,440\end{array}$

Hence, $p{}_3=328,440$