In initial tests of the Salk vaccine, 33 of 200,000 vaccinated children later developed polio. Of 200,000

Question:

In initial tests of the Salk vaccine, 33 of 200,000 vaccinated children later developed polio. Of 200,000 children vaccinated with a placebo, 115 later developed polio. At the 0.01 level of significance, test the claim that the Salk vaccine is effective in lowering the polio rate. Does it appear that the vaccine is effective?