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 600 minutes?
A)0
B)0.023
C)0.841
D)0.977
E)None of the above

Question

Quizplus · Accepted Answer

We need to find P(X<600), where X is the number of cell phone minutes used by a high school senior. We can standardize X using the formula:

z = (X - μ) / σ

where μ is the mean and σ is the standard deviation. Substituting the given values, we get:

z = (600 - 500) / 50 = 2

Using a standard normal table or calculator, we can find that the probability of getting a z-score less than 2 is approximately 0.977. Therefore, the probability of a student using fewer than 600 minutes is 0.977, or 97.7%.

The Number of Cell Phone Minutes Used by High School