Use the sample data and confidence level given below to complete parts (a) through (d). A drug is used to help prevent blood clots in certain patients. In clinical trials, among 4198 patients treated with the drug, 119 developed the adverse reaction of nausea. Construct a 90% confidence interval for the proportion of adverse reactions. a) Find the best point estimate of the population proportion p. (Round to three decimal places as needed.) b) Identify the value of the margin of error E. E = (Round to three decimal places as needed.) c) Construct the confidence interval.