There are 90 patients with a disease T that is very difficult to treat and has taken the same routine drug.The patients were divided into two equal groups. The first group was given an experimental drug W, which is used to treat T, and the second group was given a placebo without W. Statistics ten years later showed that 44 people died in both groups
Among the patients who died above, the average year of death in the second group was two years earlier than that in the first group
the experimental drug was ineffective.