Join the IDNLearn.com community and start finding the answers you need today. Our community is ready to provide in-depth answers and practical solutions to any questions you may have.

Three out of nine students in the computer club are getting prizes for first, second, and third place in a competition.

How many ways can first, second, and third place be assigned?

[tex]\[ { }_9 P_3 = \frac{9!}{(9-3)!} \][/tex]

A. 3
B. 84
C. 504
D. 2048


Sagot :

To determine the number of ways to assign first, second, and third place to three students out of nine, we need to calculate the number of permutations of 9 items taken 3 at a time. This is represented by the permutation formula [tex]\(P(n, k)\)[/tex], where [tex]\(n\)[/tex] is the total number of items and [tex]\(k\)[/tex] is the number of items to arrange.

The permutation formula is given by:
[tex]\[ P(n, k) = \frac{n!}{(n - k)!} \][/tex]

In this problem, [tex]\(n = 9\)[/tex] and [tex]\(k = 3\)[/tex]. Plugging these values into the formula, we get:
[tex]\[ P(9, 3) = \frac{9!}{(9 - 3)!} = \frac{9!}{6!} \][/tex]

Here, [tex]\(9!\)[/tex] (9 factorial) means the product of all positive integers up to 9:
[tex]\[ 9! = 9 \times 8 \times 7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1 \][/tex]

And [tex]\(6!\)[/tex] (6 factorial) means the product of all positive integers up to 6:
[tex]\[ 6! = 6 \times 5 \times 4 \times 3 \times 2 \times 1 \][/tex]

We can simplify the fraction because [tex]\(9!\)[/tex] contains all the terms of [tex]\(6!\)[/tex] as factors:
[tex]\[ \frac{9!}{6!} = \frac{9 \times 8 \times 7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1}{6 \times 5 \times 4 \times 3 \times 2 \times 1} \][/tex]

By canceling out the common [tex]\(6 \times 5 \times 4 \times 3 \times 2 \times 1\)[/tex] terms in the numerator and the denominator, we are left with:
[tex]\[ \frac{9 \times 8 \times 7 \times (6!)}{6!} = 9 \times 8 \times 7 \][/tex]

Calculating the remaining product:
[tex]\[ 9 \times 8 = 72 \][/tex]
[tex]\[ 72 \times 7 = 504 \][/tex]

Therefore, the number of ways to assign first, second, and third place to the students is:
[tex]\[ 504 \][/tex]
Thank you for contributing to our discussion. Don't forget to check back for new answers. Keep asking, answering, and sharing useful information. For trustworthy and accurate answers, visit IDNLearn.com. Thanks for stopping by, and see you next time for more solutions.