can someone help me solve this problem seafch go book contents Answer 14. SAT coaching: A sample of 32 students took a class designed to improve their SAT math scores. Following are their scores before and after the class. Before After 383 334 378 467 470 473 443 459 426 493 382 473 408 433 478 502 420 368 396 488 489 473 448 473 428 525 382 474 407 434 490 508 430 394 Solution a) Calculating the standard deviation of the differences , s = 13.56075784 Thus, the standard error of the difference is sD = s/sqrt(n): sD = 2.397225957 Calculating the mean of the differences (third column): XD = 12.90625 For the 0.95 confidence level, alpha/2 = (1 - confidence level)/2 = 0.025 t(alpha/2) = 2.039513446 lower bound = [X1 - X2] - t(alpha/2) * sD = 8.017075427 upper bound = [X1 - X2] + t(alpha/2) * sD = 17.79542457 Thus, the confidence interval is ( 8.017075427 , 17.79542457 ) [ANSWER] ************************** b) YES, IT CONTRADICTS IT. The confidence interval is totally less than 20 points. [CONCLUSION].