Your Textbook Compares the Results of a Regression of Test $\widehat{\text { TestScr }}$

Essay

Your textbook compares the results of a regression of test scores on the student-teacher ratio using a sample of school districts from California and from Massachusetts. Before standardizing the test scores for California, you get the following regression result:
$\widehat{\text { TestScr }}$ ^{= 698.9 - 2.28×STR}
n = 420, R2 = 0.051, SER = 18.6
_{In addition, you are given the following information: the sample mean of the student-teacher ratio is 19.64 with a standard deviation of 1.89, and the standard deviation of the test scores is 19.05.
a. After standardizing the test scores variable and running the regression again, what is the value of the slope? What is the meaning of this new slope here (interpret the result)?
b. What will be the new intercept? Now that test scores have been standardized, should you interpret the intercept?}
c. Does the regression R2 change between the two regressions? What about the t-statistic for the slope estimator?