5109's The results for the nal exam were normally distributed with a standard deviation of 10 and a mean of 65%. If an A grade is 80 and above what percent of students received an A? What is the probability of a randomly selected student failing (a fail grade is anything below 50). If there are 45 students how many would fail? A student tells you they scored in the top 10% of the class. What is the minimum grade they achieved? The instructor would like to reduce the percentage of failures to 5%. He proposed to do this by eliminating some of the easier and some of the more difcult questions. He expects the same average but a lower standard deviation. What standard deviation would he need to reach his objective