Passage Summary: Computer chips have been getting twice as fast every year and a half for a long time. However, for about ten years starting in the 90s, making them twice as fast also meant they cost twice as much to build.

Reasoning: Transistor counts and computing speeds have doubled every 18 months for decades, and during a specific ten-year window, every doubling of speed was accompanied by a doubling of production costs.

Analysis: This is a quantitative inference problem. We are given two rates: speed doubles every 18 months, and during a certain period, cost doubles whenever speed doubles. By combining these, we can infer that during that specific period, the cost of producing a microchip also doubled approximately every 18 months. Look for an answer that synthesizes these two facts into a single statement about the rate of cost increase.