搜题请搜索小程序“爱下问搜题”
问题 填空题

已知随机变量X1，X2…，Xn相互独立，且有相同的方差σ2(≠0)，记

，则

=______；X1与

的相关系数ρ=______．

答案

参考答案：

解析： 应用数字特征性质与定义直接计算．
由于X1，…，Xn相互独立，且DXi=σ2，故


单项选择题 案例分析题

患者男性，30岁，反复心悸3个月，再发1小时急诊，体检心率210次/分，心律齐，无心脏杂音。

为预防疾病的复发，下列哪一种治疗应首先考虑（）

A.颈动脉窦按摩

B.经导管射频消融术

C.普罗帕酮

D.β受体阻滞剂

E.洋地黄
查看答案
填空题


What are the challenges facing multinationals that want to build their brands in China —I think the first thing is ignorance. There’s a huge (1) of the complexity in China, which is more complex than Europe. There are different rules of law, which (2) a significant factor. There are different (3) , Cantonese and Mandarin and lots of others in (4) , and dialects like Sichuan versions. You have problems of distribution. (5) Chinese brands have been (6) local because of the size of the market and the transportation system, What’s (7) built up there is a sort of a pride in localness.
How can companies build their brands in China —China is a place where (8) have to be very patient and you’ve got to build (9) time. You can’t go in (10) invest short-term and then pull out (11) then try to get back in (12) . It’s about being consistent, steady, building (13) reputation, building confidence and then rewards will (14) . It’s a consistent ability to anticipate need. It’s insightfulness that helps brands to (15) ahead.
How are local Chinese brands doing against the multinationals —China’s been built (16) local brands and there are a billion of them and they are (17) spending sums of money locally that really dominate the (18) . But the future is Chinese brands moving outside of (19) and marketing globally, because China’s got to move from a commodity economy to a (20) sophisticated economy, which fundamentally (21) brands. There isn’t a major economy in the world that (22) based upon producing great brands, because they provide far better margins and more sustainable (23) .
Has Asia produced any truly global brands —Japan has. Some of the major companies (24) do really very well with brands. In Korea, some of them (25) but some of them need to catch up in terms of understanding how to really build global brands.
查看答案