Final answer:
A score of X = 50 is considered a central score for populations A and D, and an extreme score for populations B and C.
Step-by-step explanation:
In order to determine whether a score of X = 50 is considered a central or extreme score, we need to compare it to the population mean and standard deviation.
a. For population A with a mean (μ) of 45 and standard deviation (σ) of 10, a score of X = 50 would be considered a central score, as it falls within two standard deviations of the mean.
b. For population B with a mean (μ) of 45 and standard deviation (σ) of -2, a score of X = 50 would be considered an extreme score, as it falls outside the possible range of values.
c. For population C with a mean (μ) of 90 and standard deviation (σ) of 20, a score of X = 50 would be considered an extreme score, as it falls far below the mean.
d. For population D with a mean (μ) of 60 and standard deviation (σ) of 20, a score of X = 50 would be considered a central score, as it falls within one standard deviation of the mean.