The mean score of a college entrance test is 500; the standard deviation is 75. The scores are normally distributed. What percent of the students scored below 320?
A)About 50.82%
B)About 34.13%
C)About 7.86%
D)About 0.82%

Question

Quizplus · Accepted Answer

To find the percentage of students who scored below 320, we calculate the z-score using the formula z = (X - μ) / σ, where X is the score (320), μ is the mean (500), and σ is the standard deviation (75). Plugging in the values, we get z = (320 - 500) / 75 = -180 / 75 = -2.4. Looking up a z-score of -2.4 in a standard normal distribution table or using a calculator, we find that the percentage of students scoring below this z-score is about 0.82%.

The Mean Score of a College Entrance Test Is 500;