Rose and Liz both belong to a club of 20 members. A committee of 4 is to be selected at
random from the 20 members. Find the probability that both Rose and Liz will be
selected

Respuesta :

Using the hypergeometric distribution, it is found that there is a 0.0316 = 3.16% probability that both Rose and Liz will be  selected.

Hypergeometric distribution:

[tex]P(X = x) = h(x,N,n,k) = \frac{C_{k,x}C_{N-k,n-x}}{C_{N,n}}[/tex]

[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]

The parameters are:

  • x is the number of successes.
  • N is the size of the population.
  • n is the size of the sample.
  • k is the total number of desired outcomes.

In this problem:

  • Club has 20 members, hence [tex]N = 20[/tex]
  • The committee has 4 members, hence [tex]n = 4[/tex]
  • Rose and Liz are 2 of the members, hence [tex]k = 2[/tex]

The probability that both are selected is P(X = 2), hence:

[tex]P(X = x) = h(x,N,n,k) = \frac{C_{k,x}C_{N-k,n-x}}{C_{N,n}}[/tex]

[tex]P(X = 2) = h(2,20,4,2) = \frac{C_{2,2}C_{18,2}}{C_{20,4}} = 0.0316[/tex]

0.0316 = 3.16% probability that both Rose and Liz will be  selected.

A similar problem is given at https://brainly.com/question/24826394