Slutsky's theorem

Slutsky's Theorem is a mathematical way of predicting the behavior of a group of things when we change something. It's named after Russian economist Eugeni Slutsky, who first wrote about it in 1912.

Let's say you have a group of toy cars that you want to race on a track. You also have a special car that can go faster. Slutsky's theorem gives us a way to predict what will happen when we put the special car on the track.

The theorem says that if we make a change to one of the cars (like adding the special car to the track), then the average speed of the whole group of cars will change in a predictable way. It will be some combination of the speed of the cars before the change, and the speed of the special car.

So if we want to know how much faster the average speed of the toy cars will be when we add the special car, Slutsky's theorem can help us figure it out.