Jonas Salk's polio vaccine trials of 1954 involved giving placebos to 201,229 children and the polio vaccine to 200,745 children.Out of the placebo group,142 children developed polio,whereas 57 children from the vaccine group developed polio.Approximately how many more times likely was a child to develop polio if he or she were NOT vaccinated?

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The rate of polio in the placebo group was 142/201,229, and in the vaccine group, it was 57/200,745. The ratio of these rates is approximately 3, indicating that children were about three times more likely to develop polio if they were not vaccinated.

Jonas Salk's Polio Vaccine Trials of 1954 Involved Giving Placebos