A clinical trial is run to assess the effects of different forms of regular exercise on HDL levels in persons between the ages of 18 and 29. The number of hours of aerobic exercise was assessed over a 12-week period and the HDL levels are measured at the end of this period. The regression equation was calculated and is as follows : y(HDL)=54.6+2.22(hours of exercise) Estimate the HDL level for a person who does not exercise . Please round the answer to one decimal place .