Suppose that a researcher, using data on class size (CS)(CS)and average test scores from 103 third-grade classes, estimates the OLS regression

\widehat {Testscore}=556.828-6.2274CS, \text{ R}^2=.09, \text{SER}=12.3.

(a) A classroom has 20 students. The regression's prediction for that classroom's average test score is__ . (Round your response to two decimal places.)

(b) Last year a classroom had 17 students, and this year it has 21 students. The regression's prediction for the change in the classroom average test score is__ . (Round your response to two decimal places.)

(c) The sample average class size across the 103 classrooms is 22.90.The sample average of the test scores across the 103 classrooms is ___. (Hint: Review the formulas for the OLS estimators.) (Round your response to two decimal places.)

(d) The total sum of squares is ___ . (Hint: Review the formulas for the \text{R}^2R2 and \text{SER}.SER.) (Round your response to the nearest whole number.)