To test the effectiveness of a new cold vaccine, a random sample of 50 people was selected. They were divided in two groups: one consisted of 30 people who received the vaccine, and the other who did not receive the vaccine .What can we conclude about the effectiveness of this new cold vaccine (at a 5% level of significance) if in the first group 9 of the 30 who received the vaccine caught the cold, while in the other group 11 of the 20 people who did not receive the vaccine caught the cold.