You can square the whole problem to cancel out the square root. Might make things easier.
Pick 1: 3 apples out of 11 pieces of fruit → 3/11
Pick 2: 4 oranges out of 10 pieces of fruit → 4/10 = 2/5
Pick 1 AND Pick 2
3/11 x 2/5 = 6/55
Since the diameter of the cylinder is 10, its radius is half that, or 5, thus
So what it is asking you to do is compare the amount of oats to the other ingredients. ex, 2 cups of oats for every 0.5 cup of quinoa. just do that for the rest of them