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 more than 350 minutes?
A)0.001
B)0.999
C)0.618
D)0.382

Question

Quizplus · Accepted Answer

To find the probability that a student uses more than 350 minutes, we need to find the area to the right of 350 under the normal curve. 
Using the z-score formula, we get:
z = (350-500)/50 = -3
Using a standard normal table, we can find that the probability of a z-score less than -3 (which is the same as the probability of a score greater than 350) is approximately 0.001. 
Therefore, the probability that a student uses more than 350 minutes is 0.001. 
So, the best choice is B.

The Number of Cell Phone Minutes Used by High School