Scores on a statistics final in a large class were normally distributed with a mean of 70 and a standard deviation of 6.5. Find the following probabilities, round to the fourth. (Round all z-scores to two decimal places and all probabilities to four decimal places.) a) What is the probability 13 randomly chosen scores had an average greater than 76? Would it be unusual or usual for this to happen? 0 unusual O usual Shade: Left of a value v . Click and drag the arrows to adjust the values. -4 -2 1 -1 3 -1.5 b) What is the probability 10 randomly chosen scores had an average less than 63? P(x