A normal distribution has a mean of µ = 40 with σ = 10.If a vertical line is drawn through the distribution at X = 55,what proportion of the scores are on the right side of the line?
A)0.3085
B)0.6915
C)0.0668
D)0.9332

Question

Quizplus · Accepted Answer

To find the proportion of scores to the right of X = 55 in a normal distribution with a mean (µ) of 40 and a standard deviation (σ) of 10, we first calculate the z-score for X = 55 using the formula z = (X - µ) / σ = (55 - 40) / 10 = 1.5. Looking up the z-score of 1.5 in a standard normal distribution table or using a calculator, we find that the area to the left of this z-score is approximately 0.9332, meaning the area to the right (which represents the proportion of scores greater than X = 55) is 1 - 0.9332 = 0.0668.

A Normal Distribution Has a Mean of µ = 40