SAT Question 555939d2: Ratios Rates Proportional Relationships And Units answer and explanation with Desmos solution

Choice C is correct. It’s given that $8$ out of $300$ customers in a random sample said they would be interested in the new plan. This means the fraction of sampled customers who said they would be interested is $\frac{8}{300}$. Multiplying this fraction by the total customer population yields $(\frac{8}{300})(30,000)$, or $800$. Therefore, the best estimate of the total number of customers who would be interested in the new service plan is $800$.