If a random sample of 300 children is selected, let X be the number of these children who have been diagnosed with ASD. What distribution does X follow? What is the expected value and standard deviation of X?

Respuesta :

Answer:

The random variable X follows a Binomial distribution.

[tex]E(X)=X\\SD(X)=\sqrt{\frac{X(300-X)}{300}}[/tex]

Step-by-step explanation:

The random variable X defined as the number of children who have been diagnosed with ASD.

The random sample of children selected is of size n = 300.

The probability of children diagnosed with ASD is, [tex]P(X)=p=\frac{X}{300}[/tex].

A children diagnosed with ASD is independent of all the others.

The random variable X follows a Binomial distribution.

[tex]X\sim Bin(n=300, p=\frac{X}{300})[/tex]

The expected value of X is:

[tex]E(X)=np=300\times \frac{X}{300}=X[/tex]

The standard deviation of X is:

[tex]SD(X)=\sqrt{np(1-p)}=\sqrt{300\times \frac{X}{300}[1-\frac{X}{300}]}=\sqrt{\frac{X(300-X)}{300}}[/tex]