You have data with dependent variable y and independent variable as x a. Fit a linear regression model and write down the least squares equation b. Propose a new model to improve the model fit. Hint: construct a scatterplot for the data. What type of relationship, linear or curvilinear, appears to exist? you may consider nonlinear model, e.g., quadratic model. c. Run a new model based on your recommendation from b. and write down the least squares equation d. Does the new model improve the overall model fit? Why? Please write down the corresponding model results.