Hoeffding's inequality has a free parameter in your question, namely

. It lest you say that since you have 10 samples, if you want to be 80% sure of the distribution of marbles in the jar (

), then the jar is at most

percent different from the sample.

where

substituting from your example:

simplifying:

so we think that with 80% confidence, the jar is at least 10.2% green.

We probably need a bigger N!