Which figure represents the incidence rate per 100,000 people?

• A. 1.75 million occur annually
• B. 506.4 per 100,000
• C. $80 billion
• D. 4 million

Answer: (B)

Incidence rate per 100,000 people measures how many new cases occur in a population, scaled to a standard population of 100,000 to allow comparisons across different population sizes. It’s calculated as new cases divided by the population, then multiplied by 100,000. This is a rate, not a raw count or a cost.

Among the options, the figure expressed as per 100,000 is 506.4 per 100,000, which correctly represents an incidence rate. The other numbers are a total count (1.75 million or 4 million) or a dollar amount ($80 billion), which are not rates. For example, if you had 5,000 new cases in a population of 1,000,000, the incidence rate would be (5,000 / 1,000,000) × 100,000 = 500 per 100,000.