FITTING A REGRESSION LINES

(a) You will use the data provided in the file "varities2018.csv" to investigate the effect of nitrogen use on crop yield. The data set has 240 rows; the rest 120 observations are for a traditional crop variety and the next 120 for a modern crop variety. Present a table summarizing the data. The summaries should be organized by crop variety and should include the following values for nitrogen and yield: the minimum, maximum, median, mean, standard deviation and coefficient of variation values.
(b) Fit a linear regression model for the traditional variety and describe the results. Your model should have yield as the 'y' variable and nitrogen as the 'x' variable. As part of your results description, write out the estimated equation for the relationship between
yield (y) and nitrogen (n) together with the R-squared value. Interpret the results.
(c) Do the same for the modern variety. 
(d) Plot the raw data together with the regression lines (all in one plot). Use colours and legends to identify the data and the two regression lines.