A circular pie chart has a total area of 48 square inches. If one sector of the chart represents a central angle of 90°, what is the area…

A $90°$ sector is $\frac{90}{360} = \frac{1}{4}$ of the whole circle, so its area is one quarter of the total: $48 \times \frac{1}{4} = 12$ square inches, choice C. Choice A (24) takes one half, which would be a $180°$ sector. Choice B (16) takes one third, which would be $120°$. Choice D (36) is three quarters, the area of the rest of the circle, not the sector. Because the total area is given, you do not need the radius. Just multiply by the fraction of the circle.