Consider a population with 3 observations: 6, 10 and 12. You use simple random sampling without replacement to select a sample of 2 observations. What is the probability that the sample mean is larger than 8?

Respuesta :

Answer:

[tex]\dfrac{2}{3}[/tex]

Step-by-step explanation:

Given that:

The number of observations is:

6, 10, 12

If we are to use a simple  random sampling without replacement, then we will have:

(6,10)  (6,12)  (10,12)

Here;

the sample size n = 2

The population size N = 3

For (6,10) ; The sample mean = [tex]\dfrac{6+10}{2}[/tex]

= [tex]\dfrac{16}{2}[/tex]

= 8

For (6,12) ; The sample mean = [tex]\dfrac{6+12}{2}[/tex]

= [tex]\dfrac{18}{2}[/tex]

= 9

For (10, 12) ; The sample mean = [tex]\dfrac{10+12}{2}[/tex]

= [tex]\dfrac{22}{2}[/tex]

= 11

The probability distribution of sample mean(x) is:

X           8           9          11

P(X=x)    [tex]\dfrac{1}{3}[/tex]          [tex]\dfrac{1}{3}[/tex]           [tex]\dfrac{1}{3}[/tex]

Thus, the probability that the sample mean  is larger than 8 is:

P(X> 8) = P(X = 9) + P(X + 11)

P(X> 8) = [tex]\dfrac{1}{3}+\dfrac{1}{3}[/tex]

P(X > 8) = [tex]\dfrac{1+1}{3}[/tex]

P(X> 8) = [tex]\dfrac{2}{3}[/tex]