Four different designs for a digital computer circuit are being studied in order to compare the amount of noise present. The following data have been obtained: Circuit Design Noise Observed 1 19 20 19 30 8 80 61 73 56 80 3 47 26 25 35 50 4 95 46 83 78 97 (a) Is the amount of noise present the same for all four designs? Use a = 0.05. (b) Compute a 99% confidence interval of the mean of circuit design 3. (c) Compute a 95% confidence interval estimate of the mean difference between circuit designs 4 and 3. Is the amount of noise present the same for designs 3 and 4? Use a = 0.05.