Final answer:
The question is about calculating the prevalence of BMI categories in a sample. After adjusting for the changes in categories, the prevalence of normal weight, overweight, and obese remain at 56%, 24%, and 20% respectively in the sample of 6250 since the changes balanced out.
Step-by-step explanation:
The student's question is about calculating the prevalence of different BMI categories within a sample population of 6250 people. Initially, 3500 individuals had a BMI between 20 to 25 (normal weight), 1500 had a BMI between 25 to 30 (overweight), and 1250 had a BMI greater than 30 (obese).
After adjustments where 50 people lowered their BMI from >30 to 25-30 and an equal number switched from 25-30 to >30, the prevalence of each category can be recalculated. The prevalence is a way of showing the proportion of individuals within a certain BMI range in the population.
After recalculation, the new numbers will be 3500 in the normal weight category, 1500 in the overweight category, and 1250 in the obese category, as the 50 individuals moving between categories cancel each other out. Therefore, the prevalences are 56% (3500/6250 x 100), 24% (1500/6250 x 100), and 20% (1250/6250 x 100), respectively.