3) An investigation is conducted to investigate the weights among the students at School Alpha. The investigator knows that the average weight of students at the school is distributed by normal distribution. A random sample of 10 students are randomly selected from the school and their weights are measured as follows 42,45,56,72,83,60,71,48,50,62 a) Propose a pivotal quantity that can be used to estimate confidence interval and explain the choice of the pivotal quantity. b) Calculate the 95% confidence interval for the average weight of students at School Alpha