At a cross-sectional survey time point, a town of 10,000 persons has 380 preexisting cases of a chronic disease and 120 new cases identified that day. Which of the following is the best description of the prevalence proportion at that time?

Prevalence proportion should be reported as raw count only, so the correct answer is 500 cases without converting to a percentage because proportions are unnecessary for cross-sectional data.

Prevalence equals only the number of new cases divided by the population at risk, so 120 / (10,000 - 380) ≈ 1.23%, because preexisting cases must be excluded from the denominator.

Prevalence proportion equals the number of preexisting cases divided by the population at risk who did not have disease, so 380 / 9,620 ≈ 3.95%.

Prevalence proportion equals total cases (preexisting + new) divided by total population: (380 + 120) / 10,000 = 500 / 10,000 = 5.0%, representing the snapshot of disease burden.