We have 7 boys and 3 girls in our church choir. There is an upcoming concert in the local town hall. Unfortunately, we can only have 5 youths in this performance. This performance team of 5 has to be picked randomly from the crew of 7 boys and 3 girls. What is the probability that exactly 4 boys are picked in this team of 5?

Respuesta :

Answer:

  105/252 = 0.41666...

Step-by-step explanation:

There are (7C4)(3C1) = (35)(3) = 105 ways to choose exactly 4 boys. There are 10C5 = 252 ways to choose 5 youths, so the probability that a randomly chosen team will consist of exactly 4 boys is ...

  105/252

_____

nCk = n!/(k!(n-k!))

Answer:

There is a 41.67% probability that exactly 4 boys are picked in this team of 5.

Step-by-step explanation:

The order is not important, so we use the combinations formula.

[tex]C_{n,x}[/tex] is the number of different combinatios of x objects from a set of n elements, given by the following formula.

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

Number of desired outcomes.

Four boys and one girl: So

[tex]C_{7,4}*C_{3,1} = \frac{7!}{4!(7-4)!}*\frac{3!}{1!(3-1)!} = 35*3 = 105[/tex]

Number of total outcomes:

Combination of five from a set of 10.

So

[tex]C_{10,5} = \frac{10!}{5!(10-5)!} = 252[/tex]

What is the probability that exactly 4 boys are picked in this team of 5?

[tex]P = \frac{105}{252} = 0.4167[/tex]

There is a 41.67% probability that exactly 4 boys are picked in this team of 5.