Question 1068944
first you find the z-score.


the z-score is equal to (x-m)/s


x is the x-score
x is the raw score.
m is the mean.
s is the standard deviation.


the z-score in this case is z = (120-100)/15 = 20/15 = 4/3 = 1.33.....


use a z-score calculator to the highest degree of accuracy that it possesses and the probability becomes .9087887181 which is equal to roughly 90.88%.


closest selection you have is 90.15%, even though it's not right on.


a normal distribution is assumed.