Question

Within a population having a standard deviation of 20, the raw score X=75 has a z-score of -1.25. What is the mean for the population? a u=100 b u=125 c u=90 d u=50

Answer 1

The mean (μ) of the population is 100, calculated using the z-score formula with the given standard deviation and raw score.

Step-by-step explanation:

Given that the standard deviation (σ) is 20, and the z-score for a raw score (X) of 75 is -1.25, we can use the z-score formula to find the mean (μ) of the population:

Z = (X - μ) / σ

Plugging in the given values, we get:

-1.25 = (75 - μ) / 20

Multiplying both sides by 20, we have:

-25 = 75 - μ

Add μ to both sides and subtract 25 from both sides to solve for μ:

μ = 75 + 25 = 100

The mean of the population is 100. Option a is the correct answer.