statistics
posted by Anonymous .
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?

Use zscores.
Formula:
z = (x  mean)/sd
mean = 500
sd = 50
x = 350
Substitute the values into the formula and find z. Use a ztable to determine your probability.