Data Set 7-5: Suppose you knew that a population had a mean of 150 and a standard deviation of 50.
-Use Table C to answer questions about Data Set 7-5. The proportion of the population with scores less than 225 is
A) .9332
B) .4332
C) .05668

Question

Quizplus · Accepted Answer

To find the proportion of the population with scores less than 225, you calculate the z-score using the formula z = (X - μ) / σ, where X is the value in question, μ is the mean, and σ is the standard deviation. For X = 225, μ = 150, and σ = 50, the z-score is (225 - 150) / 50 = 1.5. Looking up a z-score of 1.5 in Table C (a standard normal distribution table), you find the proportion of the population below this z-score is approximately .9332.

Data Set 7-5: Suppose You Knew That a Population Had