Richard has just been given an 11-question multiple-choice quiz in his history class. Each question has five answers, of which only one is correct. Since Richard has not attended a class recently, he doesn't know any of the answers. Assuming that Richard guesses on all 11 questions, find the probability that he will answer at least 4 questions correctly. (Round your answers to the nearest thousandth.)

Explain how you got your answer. Be specific. If you used a calculator explain clearly how. If you used a formula, show your work.