参数
参考答案：
反映总体某个变量的综合描述，有平均数、方差等，可由样本统计值来估计。
为了解全国初中生的睡眠状况，比较适合的调查方式是______．
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 ？
. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life ？