Respuesta :
Using the combination formula, it is found that the number of ways by which the runners for the finals can be decided is given by:
B. 126.
The order in which they finish is not important, as all of the first four runners go to the finals, hence the combination formula is used to solve this question.
What is the combination formula?
[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by:
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
In this problem, 4 runners are selected from a set of 9, hence the number of ways is given by:
[tex]C_{9,4} = \frac{9!}{4!5!} = 126[/tex]
Which means that option B is correct.
More can be learned about the combination formula at https://brainly.com/question/25821700
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