Statistics / Empirical Rule. please help
 

im posting this here because i am about to freak the fuck out trying to figure this out! and because i dont know of any other boards with as much traffic. if you know anything about college statistics, can you please help me?

http://www.nku.edu/~statistics/212_N...stribution.htm

on problem B, they are coming up with .2123 and .4032

please help me understand where the fuck those numbers are coming from?!

thanks to anyone that bites.