Yup, this is the right answer... Those percentages are not a percent of the total contents...
The FDA has set certain amounts of all of the various nutrients and substances found in foods that the body needs per day... These percentages are based on a 2000 calorie/day diet, so it will vary from person to person (personally, I don't think I've ever eaten only 2000 calories in a day)
That juice contains 20% more than the value they have set for vitamin C... You'd get 120% of your required daily vitamin C by drinking one serving of that juice...
That juice contains 20% more than the value they have set for vitamin C... You'd get 120% of your required daily vitamin C by drinking one serving of that juice...
Which doesn't really matter, because the majority of Vitamin C is just... gotten rid of.