In this problem set, we practice fitting a linear model to make predictions. As always, we start by loading and looking at the data: ## load and look at the data grades < read.csv("grades. csv") # reads and stores data head(grades) # shows first observations ## midterm final overall gradeA ## 1 79.25 47.00 69.2 0 ## 2 96.25 87.75 94.3 1 ## 3 58.25 37.75 62.0 0 ## 4 54.50 62.00 72.4 0 ## 5 83.00 39.75 72.4 0 ## 6 41.75 49.50 59.5 0 1. In this dataset, what does each observation represent? (5 points) 2. What should be our X variable? In other words, which variable are we going to use as the predictor? (5 points) 3. What should be our Y variable? In other words, which variable are we going to use as the outcome variable? (5 points)