Richard Has Been Given a 7-Question Multiple-Choice Quiz in His

Multiple Choice

Richard has been given a 7-question multiple-choice quiz in his history class. Each question has three answers, of which only one is correct. Since Richard has not attended the class recently, he doesn't know any of the answers. Assuming that Richard guesses on all 7 questions, find the probability that he will answer at least 6 questions correctly. Round your answer to the nearest thousandth.

A) 0.006
B) 0.007
C) 0.857
D) 0.286
E) 0.500