What formula could I use for this

14. The weights of bushels of com produced by a large farm are approximately normally distributed with a mean of 89.46 pounds and a standard deviation of 2.31 pounds. A store is buys 5 bushels of corn from the farm. Assume the 5 bushels the store receives is a random sample of all bushels of corn the farm produces. What is the approximate probability that the 5 bushels will have a mean weight of more than 90 pounds? 15. A week before final examinations, a random sample of 813 students from a large college was asked if they for their final examinations. Based on this random sample, a 90%