标题: GWD-TN-19 [打印本页] 作者: wynyy2000 时间: 2011-5-20 08:56 标题: GWD-TN-19 In Patton City, days are categorized as having heavy rainfall (more than two inches), moderate rainfall (more than one inch, but no more than two inches), light rainfall (at least a trace, but no more than one inch), or no rainfall. In 1990, there were fewer days with light rainfall than in 1910 and fewer with moderate rainfall, yet total rainfall for the year was 20 percent higher in 1990 than in 1910.
If the statements above are true, then it is also possible that in Patton City
the number of days with heavy rainfall was lower in 1990 than in 1910 the number of days with some rainfall, but no more than two inches, was the same in 1990 as in 1910 the number of days with some rainfall, but no more than two inches, was higher in 1990 than in 1910 the total number of inches of rain that fell on days with moderate rainfall in 1990 was more than twice what it had been in 1910 the average amount of rainfall per month was lower in 1990 than in 1910 答案是A，但是我没想明白 90年与10年相比，小雨，中雨都比10年少，但总体降雨量去大于10年，这只能说明90年的大雨比10年多啊，照这样推，A绝对是错的，为什么会是A？我选的是D作者: sdcar2010 时间: 2011-5-20 11:34
If all the heavy rainfall days in 1990 had 100 inches of rain and all the heavy rainfall days in 1910 had no more than 3 inches . . .
A is correct
There are only two likely possibilities for 1990 to have more total rainfalls than 1910:
1) Total rainfalls from heavy rainfalls is bigger in 1990 than in 1910. This could be done either by very heavy rains in a few days in 1990 or with more heavy rainfalls days in 1990 2) Total rainfalls from moderate/light rainfalls is bigger in 1990 than in 1910. This possibility sounds counterintuitive but is mathmatically possible. Keep in mind the definition of moderate/light rainfalls is based on a range. It is conceivable that a moderate rainfalls day could have either 1.9 inch or 1.1 inch of rain. So if all the moderate rainfall days in 1990 had 1.9 inch while all the moderate rainfall days in 1910 had only 1.1 inch, the total rainfall in 1990 could be bigger than in 1910.
Answer A points out the first possibility and is the right answer.作者: sdcar2010 时间: 2011-5-20 11:37
D is wrong because the math is wrong. Since the range of moderate rainfall is between 1 and 2 inches and the total days of moderate rainfall in 2009 is fewer than that in 2010, there is no way to get twice as much moderate rainfall in 2009 as in 2010.作者: mdautobox 时间: 2011-6-10 20:46
跟楼主犯了同样的错误~~