Final answer:
d) 80% The accepted estimate for the percentage of the population with low back pain is 80%. The average disease rate for a given disease can be calculated by averaging the extremes of the range. Without specific comparative data, the U.S. rate of 33.9% cannot be definitively classified as above or below average relative to other countries.
Step-by-step explanation:
Regarding the question about the percentage of the population that has low back pain, the most commonly accepted estimate is that 80% of adults experience low back pain at some point in their lives. Referring to the information provided, for a disease with varying rates of diagnosis in different countries, the best estimate of the average percentage affected would be found by taking the mean of the reported percentages, thus giving an approximation based on the data range provided (11.4 percent to 74.6 percent).
Considering that, if the United States has a disease rate of 33.9 percent, without additional context or comparative rates from other countries, one cannot definitively determine whether this rate is above or below average; however, if the U.S. rate is within the found range, one could infer it is somewhere mid-range. Furthermore, to compare how the United States fares relative to other countries, one would need specific rates of disease incidence per country for accurate comparison.