标题: 求教一道OG PS题 [打印本页] 作者: xingxc11 时间: 2011-8-21 22:42 标题: 求教一道OG PS题 On a recent trip, Cindy drove her car 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles per gallon that Cindy’s car got on this trip must have been between A 290/12.5 and290/11.5 (B)295/12 and 285/11.5 (C)285/12 and295/12 (D)285/12.5 and295/11.5 (E)295/12.5 and285/11.5 请大家帮我分析一下 万分感谢！作者: 超级无敌小鹤鹤 时间: 2011-8-21 22:49
就是说 Cindy一共drove了（290-5）～（290+5）；用的gasoline是（12-0.5）～（12+0.5）作者: 超级无敌小鹤鹤 时间: 2011-8-21 22:51
而miles per gallon=miles/gallon;分子范围285～295；分母范围11.5～12.5；最大值是分子最大分母最小，295/11.5；最小值是分子最小，坟墓最大，285/12.5所以最后范围285/12.5～295/11.5，选D作者: hexbin 时间: 2011-8-21 22:54
楼上+1作者: xingxc11 时间: 2011-8-22 00:08