In the initial test of salk vaccine for polio, 400,000 children were chosen and divided in two groups of 200,000. One group was vaccinated with the Salk vaccine while second group was vaccinated with the placebo. Of those vaccinated with Salk vaccine, 3 later developed polio. Of those receiving the placebo, 115 later developed polio. Test the claim that the Salk vaccine is effective in lowering the polio rate. Use a=0.01