Chapter 13.2, Problem 25HP

To determine

To find: the situation in which the probability is given by $\frac{1}{C{}_3}$ .

Answer to Problem 25HP

  $7$ objects taken  $3$  at a time.

Explanation of Solution

Given:

  $\frac{1}{C{}_3}$ .

Concept used:

According to the combination formula:

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

Where $C$ is the combination.

  $n$ is the total number of objects in the set.

  $r$ is the total number of objects in the set.

Calculation:

Here   $7$ objects taken  $3$  at a time and order is not important because it is a combination. Sample answer: A bag contains seven marbles that are red, orange, yellow, green, blue, purple, and black. The probability that the orange, blue, and black marbles will be chosen if three marbles are drawn at random can be calculated using a combination.

Hence, $7$ objects taken  $3$  at a time.