1. The problem is to understand why the aspect ratio is 4:3. 2. Aspect ratio is the ratio of width to height of an image or screen. 3. The ratio 4:3 means for every 4 units of width, there are 3 units of height. 4. To verify an aspect ratio, measure the width and height and simplify the fraction \frac{\text{width}}{\text{height}}. 5. For example, if width = 16 and height = 12, then \frac{16}{12} = \frac{\cancel{4} \times 4}{\cancel{4} \times 3} = \frac{4}{3}. 6. This simplification shows the aspect ratio is 4:3. 7. So, the aspect ratio is 4:3 because the width and height measurements reduce to the fraction 4/3 when simplified.