Consider the non-constant linear model, Yi=ax i+ϵ i, where ϵ i,1≤ i≤n, are n independent and normally distributed random variable with a common mean of zero and a common variance of σ2. (a) Argue why this model is similar to the simple linear model but where the intercept parameter is given. (b) What are the MLEs for parameters a and σ2? (c) Is the MLE for a an UBE? Is it BLUE? If not, what is the BLUE? (d) What is the mean of the MLE for σ2? In the case where it is not σ2, can you scale it so as it becomes an UB