Chevyshev's Theorem, the "at most" Case

Chevyshev's theorem is a very useful tool for finding a lower bound for the percent of data within a given interval. In this video, we use the results of the theorem to infer an upper bound for the percent of data outside an interval. This is one of the most challenging types of problems covered early on in an Intro to Statistics course. This video was taken from my website:

Chevyshev's rule,at most case,Chevyshev's Theorem,