Expected value vs. sample mean

The app to the right will take a sample from a discrete uniform distribution, which includes the numbers 1 through 9, and calculate the sample's mean. You can adjust the size of the sample using the slider. Note that the expected value of this distribution is 5.

A sample is taken, and you win twenty dollars if the sample's mean is less than 4. There's a catch: you get to pick the sample's size.

Which sample size is most likely to win you the twenty dollars?