Suppose that a random sample of size 49 is to be selected from a population with mean 49 and standard deviation 6. What is the approximate probability that Xwll be more than 0.5 away from the population mean?

a 0.4403
b) 0.6403
c) 0.8807
d) 0.0664
e) 0.5597
f) None of the above

Respuesta :

Answer:

Option e -  0.5597

Step-by-step explanation:

Given : Suppose that a random sample of size 49 is to be selected from a population with mean 49 and standard deviation 6.

To find :  What is the approximate probability that will be more than 0.5 away from the population mean?

Solution :  

Applying z-score formula,

[tex]z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

Here, [tex]\mu=49,\sigma=6, n=49[/tex]

As, probability that will be more than 0.5 away from the population mean

i.e. x=49.5,

[tex]z=\frac{49.5-49}{\frac{6}{\sqrt{49}}}[/tex]

[tex]z=\frac{0.5}{0.857}[/tex]

[tex]z=0.58[/tex]

In z-score table the value of z at 0.58 is 0.7190.

x=48.5,

[tex]z=\frac{48.5-49}{\frac{6}{\sqrt{49}}}[/tex]

[tex]z=\frac{-0.5}{0.857}[/tex]

[tex]z=-0.58[/tex]

In z-score table the value of z at -0.58 is 0.2810.

Now, probability that will be more than 0.5 away from the population mean is given by,

[tex]P=P(X>49.5)+P(X<48.5)[/tex]

[tex]P=1-P(X<49.5)+P(X<48.5)[/tex]

[tex]P=1-0.7190+0.2810[/tex]

[tex]P=0.562[/tex]

Therefore, option e is correct.