Given N = 600, M = 40, SD = 10 (Normal Distribution), approximately how many individuals would you expect to score between 20 and 30?
A) 12
B) 204
C) 300
D) 84

Question

Quizplus · Accepted Answer

To find the number of individuals scoring between 20 and 30, we first calculate the z-scores for 20 and 30. Z = (X - M) / SD, where X is the score, M is the mean, and SD is the standard deviation. For 20: Z = (20 - 40) / 10 = -2. For 30: Z = (30 - 40) / 10 = -1. Looking at a standard normal distribution table, the area between Z = -2 and Z = -1 is approximately 0.1359 (or 13.59%). Therefore, the number of individuals is 0.1359 * 600 ≈ 81.54, which rounds to approximately 84 individuals.