Having done poorly on a particular exam in a junior high school, 31 students decide to write the exam again to try and improve their mark. Results are given in the following table. Student Average Standard deviation Attempt 1 (A1) 31 54 3.4 Attempt 2 (A2) 31 57 4.7 Difference (d = A1 - A2) 31 -3.0 2.7 (a) Find a 99% confidence interval for the difference in mean scores between attempt 1 and attempt 2. (Round your answers to 4 decimal places, if needed.) (b) Based on this confidence interval, can we conclude there is a difference in mean scores between attempt 1 and attempt 2? Yes, since the interval contains 0. O No, since the interval contains 0. O Yes, since the interval is completely below 0. O No, since the interval is completely below 0. Check Previous page Nex