statistics
posted by Laura .
If the grades on a police entrance exam are normally distributed with a mean of 100 and a standard deviation of 15, what percentage of students received grades of less than 115?

Use zscores.
z = (x  mean)/sd
x = 115
mean = 100
sd = 15
Use a ztable to find probability of less than 115 using the zscore calculated above. Convert to a percent.
I hope this will help.