Answer :
Using it's concept, it is found that the probability that the special ball is chosen is given by:
[tex]p = \frac{1}{C_{n,k}}[/tex]
What is a probability?
A probability is given by the number of desired outcomes divided by the number of total outcomes.
The total number of outcomes is given by the combination of k balls from the set of n balls, given by:
[tex]C_{n,k} = \frac{n!}{k!(n - k)!}[/tex]
One ball is special, hence the probability the special ball is chosen is given by:
[tex]p = \frac{1}{C_{n,k}}[/tex]
More can be learned about probabilities at https://brainly.com/question/14398287