7. Guessing on United States Medical Licensing Examinations With n = 20 guesses and p = 0.2 for a correct answer, find P(at least 6 correct answers). Using Normal Approximation. In Exercises 5–8, do the following: If the requirements of np # 5 and nq # 5 are both satisfied, estimate the indicated probability by using the normal distribution as an approximation to the binomial distribution; if np * 5 or nq * 5, then state that the normal approximation should not be used.