mean score of 80 & standard deviation of 5

Question

The scores on a math test were normally distributed with a mean sore of 80 and a standard deviation of 5.

What percent of the students scored less than 69?

Answer 1

Pat,

 

I typically use excel for this. First you have to find how many standard deviations 69 is from 80:

(69-80)/5=-2.2

 

Then you can use a lookup table or Excel's normsdist (or norm.s.dist, depending on the version):

normsdist(-2.2,1)=1.3%