Question

Edward has to take a seven​-question ​multiple-choice quiz in his sociology class. Each question has four choices for​ answers, of which only one is correct. Assuming that Edward guesses on all seven ​questions, what is the probability that he will answer ​a) all seven questions​ correctly, ​b) exactly three questions​ correctly, ​c) at least three questions correctly.

Answer 1

I think the answer is c, at least three questions correctly because he wouldn't get all of them right and he can't a get perfect number, 3.