Answer all questions with explanation

(1 point) Coaching companies claim that their courses can raise the SAT scores of high school students. But students who retake the SAT without paying for coaching also usually raise their scores. A random sample of students who took the SAT twice found 427 who were coached and 2733 who were uncoached. Starting with their verbal scores on the first and second tries, we have these summary statistics: Try 1 Try 2 Gain n X S X S X S Coached 427 500 92 529 97 29 59 Uncoached 2733 506 101 527 101 21 52 Estimate a 98% confidence interval for the mean gain of all students who are coached. to at 98% confidence. Now test the hypothesis that the score gain for coached students is greater than the score gain for uncoached students. Let , be the score gain for all coached students. Let uz be the score gain for uncoached students. (a) Give the alternative hypothesis: # | - #2 0. (b) Give the t test statistic: (c) Give the appropriate critical value for a =5%: The conclusion is A. There is not sufficient evidence to support the claim that with coaching, the mean increase in scores is greater than without coaching. OB. There is sufficient evidence to support the claim that with coaching, the mean increase in scores is greater than without coaching