An SRS of XXXXXXXXXXhigh school seniors gained an average of ?¯=21.78x¯=21.78 points in their second attempt at the SAT Mathematics exam. Assume that the change in score has a Normal distribution with...

(a) Using the 6868 – 9595 – 99.799.7 Rule or the ?-z-table (Table A), give a 68%68% confidence interval (?,?)(a,b) for ?μ based on this sample.

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