Question

The Elgin Heart Institute performs many open-heart surgery procedures. Recently research physicians at Elgin have developed a new heart bypass surgery procedure that they believe will reduce the average recovery time. The hospital board will not recommend the new procedure unless there is substantial evidence to suggest that it is better than the existing procedure. Records indicate that the current mean recovery rate for the standard procedure is 42 days. The recovery times for a sample of 36 patients using the new procedures have a mean time of recovery of 40.2 days with a standard deviation of 5 days. At a level of significance of 0.01, is there enough evidence to conclude that the new bypass procedure does result in a shorter average recovery period?

Answer 1