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In a study of treatments for very painful "cluster" headaches, 159 patients were treated with oxygen and 160 other patients were given a placebo consisting of ordinary air. Among the 159 patients in the oxygen treatment group, 126 were free from headaches 15 minutes after treatment. Among the 160 patients given the placebo, 22 were free from headaches 15 minutes after treatment. Use a 0.05 significance level to test the claim that the oxygen treatment is effective. Complete parts (a) through (c) below. vvnal is the conclusion based on the nypoiesis test? The P-value is less than the significance level of a = 0.05, so reject the null hypothesis. There is sufficient evidence to support the claim that the cure rate with oxygen treatment is higher than the cure rate for those given a placebo. b. Test the claim by constructing an appropriate confidence interval. The 90% confidence interval is