One study assigned stroke patients at random to four treatments. Here are the data. Treatment # of patients # of strokes # of deaths Placebo 1649 250 202 Aspirin 1649 206 182 Dipyridamole 1654 211 188 Both 1650 157 185 Make a two-way table of treatment by whether or not a patient had a stroke during the two-year study period. Compare the proportion of strokes for the four treatments. Which treatment appears most effective in preventing strokes? Test if there is significant evidence that the four treatments differ in the proportion of patients who stroke? In what ways do they differ 请问一下这题要怎麽解释? 光把Frequeny打上也不能解释第一部分吧? Placebo 1649 250 15.16% Aspirin 1649 206 12.49% Dipyridamole 1654 211 12.76% Both 1650 157 9.52% 6602 824 恳请板上强者帮忙给点头绪 -- 很多时候 爱一个人爱得太深，人会醉 而恨得太久，心也容易碎 --

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