Echinacea is widely used as an herbal remedy for the common cold, but does it work? In a double-blind experiment, healthy volunteers agreed to be exposed to common-cold-causing rhinovirus type 39 and have their symptoms monitored. The volunteers were randomly assigned to take either a placebo or an echinacea supplement daily for 5 days following viral exposure. Among the 103 subjects taking a placebo, 88 developed a cold, whereas 44 of the 48 subjects taking echinacea developed a cold.1 Conduct calculation steps to determine the 95% plus four condence interval for the difference in proportions p1 p2 of individuals developing a cold after viral exposure between the echinacea treatment and the placebo. Let p1 represent the population proportion for the placebo patient population and p2 represent the population proportion for the echinacea patient population. First provide the plus four sample proportions for the placebo group 13] and the echinacea group 172. Compute the standard error SE of the difference of the proportion estimates. Provide all answers to four decimal places