Test Scores: The test scores on a 100-point test were recorded for 20 students: 71 93 91 86 75 73 86 82 76 57 84 89 67 62 72 77 68 65 75 84 (a) (3pts) Can you reasonable assume that these test scores have been selected from a normal population? Use a stem and leaf plot to justify your answer. Use R and provide your R code and the output. (b) (3pts) Calculate the mean and standard deviation of the scores. Use R and provide your code and the output. (c) (4pts) If these students can be considered a random sample from the population of all students, find a 95% confidence interval for the average test score in the population. Use R and provide your R code and the output