解析库 > 2021年6月全球GRE机经题
The traditional color of fire trucks is red, but in cities that have introduced yellow trucks into their fleets, the rate of traffic accidents per mile driven among these trucks has been far lower than the rate among red trucks. Some critics of the innovation have questioned whether this difference should be attributed to color, given that the yellow trucks were generally newer than the red trucks with which they were compared. But this criticism can be dismissed. Certainly, the mere difference in accident rates is not decisive evidence. The decisive fact is that the rates differed significantly only in the hours around dawn and dusk. At these hours, the visibility of yellow is known to be better than that of red.