STUDENT'S RESULTS IN THREE MATH PAPERS
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The following observations are the results students gained
in three math papers. They take 202 and 203 in their second
year and then 303 in their third yeard.

[1] result in 202 math paper
[2] result in 203 math paper
[3] result in 303 math paper

To help decide whether the results in the second year papers 
good predictors of outcome in 303, we could fit the model

   y = beta_0  +  beta_1 * x_1  +  beta_2 * x_2  +  e .

Here, y is the result in 303 and x_1 and x_2 are in deviation
form corresponding to the results in 202 ane 203.

1) Calculate the estimates beta_0, beta_1 and beta_2.
2) Find the predicted outcome, y_hat, for each student in 303.