问题
问答题
In a certain animal population, for each of the first 3 months of life, the probability that an animal will die during that month is 
. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life ？
答案
参考答案：
146个。
解析：
因在前3个月中每个月的死亡概率都为0.1，所以出生一个月后生存下来200(1-0.1)个；同理出生两个月后存活下来200(1-0.1)2，第三个月为200(1-0.1)3=146个。
