标题: OG11-紫91 (已搜索過，不明白題目意思) [打印本页] 作者: Kath1985 时间: 2010-2-27 13:51 标题: OG11-紫91 (已搜索過，不明白題目意思) OG11-紫91 For a light that has an intensity of 60 candles at tis source, the intensity in candles, S, of the light at a point d feet from the source is given by the formula S=60k/d^2, where k is a constant. If the intensity of the light is 30 candles at a distance of 2 feet from the source, what is the intensity of the light at a distance of 20 feet from the source? A 3/10 candle B 1/2 candle C 1 candle D 2 candle E 3 candle 答案為A
