Using confidence interval concepts, it is found that the reasonable estimate for the proportion of all American adults who believe that regular exercise is important is of 0.753.
It is the range in which a parameter is expected to be given a confidence level, has format (a,b), and the point estimate of the parameter is the mean between a and b.
In this problem, the interval is [0.726, 0.780], hence, the estimate is of:
(0.726 + 0.78)/2 = 0.753
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