In a certain study, mean symptom score (a measurement variable) standard deviation were: 0.75 0. 35 (Placebo) and 0.55 0.40 (for treated condition). There were 225 and 205 participants in placebo and the treated condition group respectively. (a) [Points=2+2] Compute 95% confidence interval for the mean symptom scores in each of the above two groups. Show your calculations of margins of error and the intervals. (b) [Point=1] Interpret the interval for the placebo group only. (c) [Points=2] For the treated condition group only: if you need to reduce the margin of error by one fourth (i.e., the new margin of error = 0.75 x margin of error in part (a)) , what should the sample size?