有一年,美国政府为了征召海军志愿兵,在各种媒介上公布征兵海报,其中特别提到:“……在1898年美国和西班牙的战争中,美国军队里士兵的死亡率是1000人中只有9人。而在这一时期的纽约市里,居民的死亡率是1000人中有16人……”显然,这段内容是在暗示参军要比待在城市里更安全。事实果真如此吗?对此我们进行数学分析。首先要明确的是,这份海报里引用的数据都是正确的, One year, in order to recruit naval volunteers, the U.S. government published conscription posters in a variety of media. In particular, it said: “...... In the war between the United States and Spain in 1898, the death rate of soldiers in the U.S. armed forces was only 1,000 among the 1,000 9, while residents in New York City during this period had a mortality rate of 16 out of 1,000 ... ”Obviously, this passage is an indication that joining the army is more secure than staying in the city. Is this really the case? For this we have a mathematical analysis. The first thing to be clear is that the data quoted in this poster is correct,