SOLUTION: Consider a normal population with µ = 25 and σ = 7.0. (A) Calculate the standard score for a value x of 27. (B) Calculate the standard score for a randomly selected

Algebra.Com
Question 701436: Consider a normal population with µ = 25 and σ = 7.0.
(A) Calculate the standard score for a value x of 27.
(B) Calculate the standard score for a randomly selected sample of 45 with xbar = 27.
(C) Explain why the standard scores of 27 are different between A and B above
please walk me through this

Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
Consider a normal population with µ = 25 and σ = 7.0.
(A) Calculate the standard score for a value x of 27.
z(27) = (27-25)/0.7 = 2.857
-------
(B) Calculate the standard score for a randomly selected sample of 45 with xbar = 27.
z(27) = (27-25)/(0.7/sqrt(45)) = 2/(0.7/sqrt(45)) = 19.166
--------
(C) Explain why the standard scores of 27 are different between A and B above
The Central Limit Theorem says:
1. The mean of the sample means = the mean of the population
2. The std of the sample means = (the std of the population)/sqrt(sample size)
-------
So the population std is much smaller that the std of the population.
As a result the z-score (which is a count of std's) is greater for
sample means than it is for an equal sample element.
============================
Cheers,
Stan H.

RELATED QUESTIONS

Please Help Consider a normal population with µ = 25 and σ = 7.0. (A) Calculate (answered by jim_thompson5910)
I am struggling with this problem...I am getting a headache because I have been working... (answered by stanbon)
Consider a normal population with a mean of 25 and standard deviation of 8.0.... (answered by stanbon)
Consider a normal population with μ = 47 and σ = 5.2. Calculate the z-score for (answered by stanbon)
Consider a normal population with μ = 36 and σ = 4.9. Calculate the z-score for (answered by ewatrrr)
Consider a normal population with μ = 43 and σ = 5.4. Calculate the z-score for (answered by abdulaleem)
Consider a population with µ=74.5 and σ=3.04. (A) Calculate the z-score for x=75.7... (answered by ewatrrr)
Consider a population with µ= 78.5 and σ= 5.24. Calculate the z score for x... (answered by edjones)
normal distribution with a mean of 61 and standard deviation of 5, how to calculate the... (answered by stanbon)