Scores on a common final exam in a large enrollment, multiple-section freshman course are normally distributed with mean72.7 and standard error of 1.31 for a sample of 100. 13.1

(a)Find the probability that the score,Xon a randomly selected exam paper is between70and80. (0.2955)

(b)Find the probability that the mean score, of38randomly selected exam papers is between70and80. (0.8977)

(c)Calculate the minimum score that need to be scored by a student for the probability to exceed 95% of marks. (51.1505)

help, how do I do PART B AND C? the numbers in the bracket are the answers but I don't know how to get it. I manage to do part a ONLY