At a high school, GPA’s are normally distributed with a mean of 2.6 and a standard deviation of 0.5. What percentage of students at the college have a GPA between 2.1 and 3.1?

Answer 1

you can play around with Z table stuff at

http://davidmlane.com/hyperstat/z_table.html

It's a handy tool.

Answer 2

2.5