SAT Question c78bb2b8: Distributions, Center & Spread answer and explanation with Desmos solution

Choice B is correct. The mean of a data set is calculated by dividing the sum of the values in the data set by the number of values in the data set. It’s given that the mean length of the $240$ gray seals from Muskeget Island was $88$ inches. This can be represented by the equation $\frac{x}{240}=88$, where $x$ represents the sum of the lengths, in inches, of the $240$ gray seals from Muskeget Island. Multiplying both sides of this equation by $240$ yields $x=(240)(88)$, or $x=21,120$ inches. It’s also given that the mean length of the $120$ gray seals from Sable Island was $94$ inches. This can be represented by the equation $\frac{y}{120}=94$, where $y$ represents the sum of the lengths, in inches, of the $120$ gray seals from Sable Island. Multiplying both sides of this equation by $120$ yields $y=(120)(94)$, or $y=11,280$ inches. Therefore, the sum of the lengths, in inches, of all $360$ gray seals is $21,120+11,280$, or $32,400$. Dividing this sum by $360$ yields $\frac{32,400}{360}$, or $90$ inches. Therefore, the mean length of all $360$ gray seals the scientist measured for this study is $90$ inches.