On a standardized exam, the scores are normally distributed with a mean of 300 and a standard deviation of 40. Find the z-score of a person who scored 310 on the exam.

To find the z-score, we can use the formula:

z = (X - μ) / σ

Where:
X = score (310)
μ = mean (300)
σ = standard deviation (40)

z = (310 - 300) / 40
z = 10 / 40
z = 0.25

So, the z-score of a person who scored 310 on the exam is 0.25.