An SRS of 450 450 high school seniors gained an average of ¯ x = 20 x¯=20 points in their second attempt at the SAT Mathematics
exam. Assume that the change in score has a Normal distribution with standard deviation σ = 49 σ=49 . (a) Find a 95 % 95% confidence interval for the mean change in score μ μ in the population of all high school seniors. (Enter your answers rounded to two decimal places.)