What is the prevalence proportion of meningitis in the region thus far this year given 39 cases among 84,000 children aged 15 years and younger?

• A. 4.1/100,000
• B. 5/100,000
• C. 46/100,000
• D. 50/100,000

Answer: (C)

The question tests how to calculate a prevalence proportion. You take the number of existing cases and divide by the population at risk, then express that ratio per a standard population size, here per 100,000.

So, 39 meningitis cases among 84,000 children aged 15 years and younger gives:

39 ÷ 84,000 = 0.000464, which is 0.0464%.

Multiplying by 100,000 to express per 100,000 people: 0.000464 × 100,000 ≈ 46.4.

Rounded, the prevalence proportion is about 46 per 100,000. The other options would require a different number of cases or a different population size (for example, 42 cases would be 50 per 100,000, and about 3–4 cases would be around 4–5 per 100,000), so they don’t match the given data.