1. A double blind, placebo-controlled, randomized comparative experiment was conducted on 3 new drugs for preventing the contraction of a particular virus. 6000 volunteers were randomly assigned to either treatment group A, B, C, or placebo. The participants were given the treatment and then 72 hours later they were exposed to the virus. After 24 additional hours, a blood test was conducted to deter double-blinding if the volunteers were now positive for the virus. After 72 hours the test was again performed. The results are given below. Conduct a test to determine if there is a difference in the 3 treatments vs the placebo 72 hours after exposure. Conduct additional tests to determine which treatment is the best. Use a significance level of 1% in all of your tests. Please explain what a double-blind, placebo-controlled, randomized comparative experiment is.

Treatment group	Group size	Number positive after 24 hours	Number positive after 72 hours
A	1490	4	102
B	1500	18	55
C	1505	22	51
Placebo	1505	300	800