Sure, let's break this down step by step to determine how many 1-year-old children have been vaccinated against some disease based on the given data.
### Step 1: Determine the total population
We need to add the populations of the different regions to find the total population of 1-year-old children:
- Population of the Americas: 2 billion
- Population of Europe: 1 billion
- Population of Africa: 1 billion
- Population of Australia and Asia: 3 billion
Adding these together:
[tex]\[
\text{Total population} = 2 + 1 + 1 + 3 = 7 \text{ billion}
\][/tex]
### Step 2: Determine the vaccination rate
The problem states that the vaccination rate is 20%. This means that out of the total population of 1-year-old children, 20% have been vaccinated.
### Step 3: Calculate the number of vaccinated children
We need to find 20% of the total population. To do this, we multiply the total population by the vaccination rate:
[tex]\[
\text{Number of vaccinated children} = \text{Total population} \times \text{Vaccination rate}
\][/tex]
Using the numbers we have:
[tex]\[
\text{Number of vaccinated children} = 7 \text{ billion} \times 0.20 = 1.4 \text{ billion}
\][/tex]
### Conclusion
Based on the provided data, 1.4 billion of the world's 1-year-old children have been vaccinated against some disease.
