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ZX-4CE338EEAC2025年10月美国A卷(数易) · 第 13 题
2025年10月美国A卷(数易) · 原库模块 1 · Q13 原库参考解析
A model estimates that the initial number of photons in an X-ray beam is 800 when the beam reaches the surface of a certain material. The model also estimates that when the beam passes through this material, the number of photons in the beam decreases by 50% for each 7 millimeters of the material the beam passes through. Which equation represents this model, where I is the estimated number of photons in the beam when the beam reaches a point x millimeters from the surface?
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