Having done poorly on a particular exam in a junior high school, 24 students decide to write the exam again to try and improve their mark. Results are given in the following table. Student n Average Standard deviation Attempt 1 (A1) 24 50 3.1 Attempt 2 (A2) 24 55 4.7 Difference (d=A- A2) 24 -5.0 2.5 (a) Find a 90% 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. No, since the interval contains O. Yes, since the interval is completely below 0. No, since the interval is completely below 0