About experimental execution: You are doing a taste test experiment on your classmates for their ability to taste
or not to taste a particular water-soluble, colorless chemical. You set out 30 identical cups, and pour the test solution into each one, half-filling the cup. The class time comes, and you are about to run your experiment, but you count your samples again and discover that there are 31 filled cups. You are reasonably certain that you counted 30 cups out originally (though there were more in the package).
What is the probability that one of your classmates receives a different sample material than you intended?