SAT Question b4912cc5: Ratios Rates Proportional Relationships And Units answer and explanation with Desmos solution

Choice D is correct. The increase in Iceland's population can be found by multiplying the increase in population density, in people per square kilometer, by the area, in square kilometers. It's given that the population density of Iceland was $2.5$ people per square kilometer in $1990$ and $3.3$ people per square kilometer in $2014$. The increase in population density can be found by subtracting $2.5$ from $3.3$, which yields $0.8$. It's given that the land area of Iceland was $100,250$ square kilometers. Thus, the increase in population is $0.8\times 100,250$, or $80,200$.

Alternate approach: It's given that the population density of Iceland, in people per square kilometer of land area, in $1990$ was $2.5$. Since the land area of Iceland was $100,250$ square kilometers, it follows that the population of Iceland in $1990$ was $2.5\times 100,250$, or $250,625$. Similarly, the population of Iceland in $2014$ was $3.3\times 100,250$, or $330,825$. The population increase is the difference in the population from $1990$ to $2014$, or $330,825-250,625$, which yields $80,200$. Therefore, Iceland's population increased by $80,200$ from $1990$ to $2014$.