12. An emergency room physician wanted to know whether there were any differences in the amount of time it takes for three different inhaled steroids to clear a mild asthmatic attack. Over a period of weeks she randomly administered these steroids to asthma sufferers, and noted the time it took for the patients’ lungs to become clear. Afterward, she discovered that 12 patients had been treated with each type of steroid, with the following sample means (in minutes) and sample variances resulting.

(a) Test the hypothesis that the mean time to clear a mild asthmatic attack is the same for all three steroids. Use the 5 percent level of significance.

(b) Find confidence intervals for all quantities μi − μj that, with 95 percent confidence, are valid.

Transcribed Image Text:

Steroid X St A 32 145 2C B 40 138 30 150