Young's modulus is a quantitative measure of stiffness of an elastic material. Suppose that for metal sheets of a particular type, its mean value and standard deviation are 85 GPa and 2.3 GPa, respectively. Suppose the distribution is normal. (Round your answers to four decimal places.) (a) Calculate P(84 ≤ X ≤ 86) when n = 16. .9812 Incorrect: Your answer is incorrect. (b) How likely is it that the sample mean diameter exceeds 86 when n = 25