Question

The mean score on the Stats exam was 75 points with a standard deviation of 5 points, and Gregor’s z-score was -3 . How many points did he score?

A. 75

B. 90

C. 65

D. 60

Answer 1

The answer is D. 60

Explanation:

We can use the formula for calculating z-score to find out how many points Gregor scored on the Stats exam. The z-score formula is:

z = (x - μ) / σ

where x is the raw score, μ is the population mean, and σ is the population standard deviation.

We know that the population mean (μ) is 75 points and the population standard deviation (σ) is 5 points. We also know that Gregor's z-score (z) is -3. Substituting these values into the formula, we get:

-3 = (x - 75) / 5

Simplifying the equation, we get:

-15 = x - 75

Adding 75 to both sides, we get:

x = 60

Therefore, Gregor scored 60 points on the Stats exam. The answer is (D) 60.