Suppose you are in the business of selling fruit salad, or you are just obsessed about perfecting your groceries. Either way, you want to know what is the exact mix of fruits to go into a fruit salad, that will minimize or maximize something. 

The first thing that comes to mind is minimizing the cost of a bowl of fruit salad. It is a very useful information, since it affects directly the types of fruit you buy in the market. And from my experience, fresh fruits aren't very cheap!

Another thing that you do is to study and find out what is the best fruit salad recipe to get you as many nutrients as possible per serving. This may take you to the realms of nutritional sciences. 

This idea is about this, a collection of ideas that came up to me about this very practical optimization problem.