Hi z = (x̄ - μ) /(170/√50) = -10/(170/√50) = -.4159 What is the probability that a sample of 50 exams will have the mean score of 490 or more if the exam scores follow the same distribution as in the past? Continous curve: P( z ≤ -.4159) = .3387 P( z ≥ -.4159) = 1 - .3387 = .6613 Wish You the Best in your Studies.