Suppose the mean percentage in Algebra 2B is 70% and the standard deviation is 8%. What percentage of students pass the class with an 86% or better?

Answer 1

You would have to assume that the variable is normally distributed and then use a z score.

Z=(x-mu)/std dev.

Z=(86-70)/8 =2

then you want the probability that Z>=2 which is approximately a little less than .0228 or 2.28%.