The number of cell phone minutes used by high school seniors follows a normal distribution with a mean of 500 and a standard deviation of 50.What is the probability that a student uses fewer than 400 minutes?
A)0
B)0.023
C)0.159
D)0.977
E)None of the above

Question

Quizplus · Accepted Answer

To find the probability that a student uses fewer than 400 minutes, we calculate the z-score: z = (400 - 500) / 50 = -2. Using the standard normal distribution table, the probability corresponding to a z-score of -2 is approximately 0.023.

The Number of Cell Phone Minutes Used by High School