Stats help on normal distribution DX

Hey there, I need help on normal distribution.


4. An investment broker reports that the annual returns on common stock and municipal bonds are both normally distributed. The stocks have a mean return of 12.4% with a standard deviation of 22.5% . On the other hand the bonds have a mean return of 5.9% with a standard deviation of 8.5% .
a) If you are a conservative investor and just don't like to lose money, which type of investment should you choose? Stocks Bonds

So what i did was divide the mean by SD = 12.4/22.5 = 0.551 Then we were to find the area between the mean and the SD (0.511), which i don't know how to get. Then we have to subtract the ### that we suppose to find by 0.5 (since the ### that we need to find is below the SD, we need to subtract). So i'm having problems trying to find the area between the mean and the SD (0.511). Please help me!

If you made this selection, what would be your probability of losing money?

I need the ### from the above question to answer this


b) If you are more ambitious an investor and would like to have the best chance of making more than 2%, which investment should you choose? Stocks Bonds

I'm guessing, you need to find the SD of z which is z= x- mean/SD is z = (o.o2- 12.4)/22.5 = (-0.55) ??? Can i get a negative number? or do i subtract mean from 2% and then divide by the SD to get 0.55. OMG i'm so lost. Then I do the same thing as the above question (which I don't understand).

If you made this choice, what would be the probability of making more than 2% ?

I need the ### from the above question to answer this

Roughly speaking, standard deviation measures "risk". The smaller the standard deviation the less risk, the larger the standard deviation, the more risk. There is no simple computational method to find values for the standard normal distribution. Either look in a table of the normal distribution or use a statistics calculator.