Question

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?

Answer 1

Use z-scores.

z = (x - mean)/sd

x = 115
mean = 100
sd = 15

Use a z-table to find probability of less than 115 using the z-score calculated above. Convert to a percent.

I hope this will help.