不过是用英语写的
问题描述：
不过是用英语写的
第一题
in a large town,one person in 80,on average,has blood of type X.how many donors must be taken at random in order that the probability of including a t least one donor of type X shall be 0.9 or more?
第二题
In the quick grow garden,plants are inspected for the presence of the deadlyu purple bug,the number of bugs per leaf is known to follow a poisson distribution with mean one
what is the probability that any one leaf on a given plant will have been attacked ie.at least one bug is found on it
我看了书 没有类似的题目
好想睡觉
答
第一题：意思是一个镇上,有血型x的人的概率是1/8,问要随机取多少个献血者的血液,才能使血库中有x型血的概率超过0.9设要m个人根据题意需要使不含x型血的概率小于0.1即（1-1/8)^m=18故至少随机取18个人的血液,才能满足...