A random sample of n = 4 scores is obtained from a population with a mean of µ = 80 and a standard deviation of σ = 10.If the sample mean is M = 90,what is the z-score for the sample mean?
A)z = 20.00
B)z = 5.00
C)z = 2.00
D)z = 1.00

Question

A random sample of n = 4 scores is obtained from a population with a mean of µ = 80 and a standard deviation of σ = 10.If the sample mean is M = 90,what is the z-score for the sample mean?​
A)​z = 20.00
B)​z = 5.00
C)​z = 2.00
D)​z = 1.00

Quizplus · Accepted Answer

The formula for calculating the z-score for the sample mean is z = (M - µ) / (σ / sqrt(n)). Substituting the values given in the question, we get z = (90 - 80) / (10 / sqrt(4)) = 2. Therefore, the correct answer is option C, z = 2.00.

A Random Sample of N = 4 Scores Is Obtained