If a test has 100 questions, each worth 1 point apiece, with 5 multiple choice answers per question, what is the probability that if someone without studying randomly guesses at the answers what would be their grade on the test be?

You should really just study for it and learn the information.

1/(5^100)=1/(7.88860905*10^69)=1.2676506*10^-70

That is the chance of you getting a perfect score guessing randomly

I think rich is asking a different question, not about a perfect score. Rich, if there were but one question with 5 choices what would the average score be? 1 out of 5, right?