if you use R to solve, please include code used

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Question 1. An instructor performs SRS on each of his 3 sections of a course using a proportional allocation scheme. Each section has the same number of students. The corresponding 95% confidence intervals for the average grade in each section, 1 to 3 are respectively (70,80), (68,72) and (64,70). Part A. Build a 95% confidence interval for the average grade in his course. Part B. The instructor decides to perform a Neyman allocation. Determine the proportion of their total sample that should come from section 1