Determine the probabilities for the following normal distributions. 
a. mean=12 standard dev= 4 P(8 -< x -<16)
b. mean= 0 standard dev: 1 P(-1.96 -< x -< 1.96) 
c. mean=0 standard dev: 1 P(-2.575 -

I tried doing it the way I learned it, but it is coming out to 0 every time which makes no sense. I'm hoping someone good at Statistics can help!!!!!