Some reason I get a different answer than the actual answer.
* = Standard Deviation, which is unknown and that is what we are solving for
ok, so here we can cut out the middle man, and equate the first and last piece, we can do that since all three pieces are equal. i don't know how you ended up with this type of equation to begin with
...........subtract 0.08 from both sides
........divide both sides by 0.2
EDIT: Oh, the last piece is what you simplified the middle piece to get. Ok. Yeah, you still do what I did for the next step