/diy/ - Do It Yourself

This is my other design question. I'll probably go with a bridge rectifier, but this question is a bit confusing because I don't understand transformer turn ratio (never really learned it), but the other two I know... I can add in a capacitor (filter) to limit it to within 5% by just using V(ripple) = V(peak) / 2 * frequency * resistor * capacitor, and just solve for the capacitor. This one is probably a lost cause to me, ah I really hope I don't get this for the actual exam. Any advice/tip is appreciated!