m-3 please help me with the below problem with step by step explanation clearly.

Needed both the parts please with a very clean and brief explanation.

3. Suppose you have reason to believe that you can predict the value of some random variable Y' from the values of another random variable X (e.g. X is the number of classes a student has missed, and Y is their score on the final exam). In the simplest scenario, the predicted value of Y would be Y = aX + b for some constants a and b (this would be called a linear predictor). The quality of this predictor can be measured using the mean square error E((Y - Y)?). (a) Show that the mean square error is minimized if we pick constants b= p- OY a = my - bux , OX where p is the correlation coefficient between X and Y. (b) Calculate the mean square error for this best linear predictor. How does the value of p affect the error