My answer:

In the argument, the experts conclude that Corpora’s citizens physical fitness level is proportional to their economical state. The experts come to this conclusion based on some Corpora’s regions where citizens used to spend a handsome amount of money on fitness-related products and services. Thus, they are physically fit. However, before the conclusion can be adequately assessed, the experts should provide three pieces of additional information to increase the persuasiveness of the suggestion.
First of all, the experts assume that the survey was conducted scientifically and is representative of Corpora’s large population. But this might not be the case. Perhaps this survey could be representative of a small region of Corpora. In addition, the experts do not mention whether the survey is based on various ages of children, men, and women or not. If either scenario proves true, the argument of the experts that the survey had been conducted scientifically does not hold water.
Moreover, the experts presume, without justification, that the citizens of Corpora’s have enough leisure time to spend in the gym or work out. However, this might not be true. For example, the citizens could spend their time doing some part-time jobs for earning extra money. Furthermore, they might prefer swimming, cycling or walking in the park for their refreshment and so they couldn’t manage extra time for doing work out or gym. If it is true that the people of Corpora’s do not have enough time to spend their time in physical fitness, then the contention of the experts is significantly hampered.
Finally, the experts assume that the recent decline in the citizens income made them spend low amounts of money on physical fitness-related products or services. Nevertheless, this might be incorrect. Perhaps the product selling companies were not well reputed in this region and they used to sell the ordinary products. It is also possible that they do not have a good gym center near their house. If the aforementioned cases turn out to be true, then the evaluation of the experts on citizens low income makes them physically unfit is considerably weakened.
In conclusion, the experts may be correct in predicting that good economic conditions can improve the physical fitness of Corpora’s people. However, as it stands now, the prediction rests on three unwarranted assumptions that dramatically hinder its validity. If the experts would like to increase the credibility of his conclusion, they need to answer the above three questions.