SAT Question 9ba3e283: Inference From Sample Statistics And Margin Of Error answer and explanation with Desmos solution

Choice C is correct. It is given that $34.6\%$ of $26$ students in Mr. Camp's class reported that they had at least two siblings. Since $34.6\%$ of $26$ is $8.996$, there must have been $9$ students in the class who reported having at least two siblings and $17$ students who reported that they had fewer than two siblings. It is also given that the average eighth-grade class size in the state is $26$ and that Mr. Camp's class is representative of all eighth-grade classes in the state. This means that in each eighth-grade class in the state there are about $17$ students who have fewer than two siblings. Therefore, the best estimate of the number of eighth-grade students in the state who have fewer than two siblings is $17\times$ (number of eighth-grade classes in the state), or $17\times 1,800=30,600$.