To find the total number of people living in Kingston County, we will multiply the number of households by the average household size.
- Number of households: \( 2 \times 10^5 = 200,000 \)
- Average household size: \( 2.5 \)
Now, we can calculate the total population:
\[ \text{Total population} = \text{Number of households} \times \text{Average household size} = 200,000 \times 2.5 \]
Calculating this step-by-step:
\[ 200,000 \times 2.5 = 200,000 \times \frac{25}{10} = \frac{200,000 \times 25}{10} = \frac{5,000,000}{10} = 500,000 \]
Thus, the total number of people living in Kingston County is:
\[ \boxed{500000} \]
In standard form, this result is \( 500,000 \), which does not require any exponents.