924北美寂静

realdj

数学记得ds有一道题讲的是一个大集合{1,2,3,4,5} A和B是这个大集合的两个子集，A^和B^分别代表A和B的非。问你A和B的交集是什么 给了两个条件 分别是A和B^的交集是{2}和A^和B的交集是{4}
阅读有一篇讲的是捆绑销售bundling 讲了两个strategy，第一个strategy是为了满足各种人的需求，举了credit card做例子，虽然你不用这个credit card的所有功能，但这些功能满足了几乎所有人的需求。第二个strategy记不清了。有一道主旨题 其中有一个选项是compare effectiveness of the two strategies 我觉得不选 因为文章总体还是在将bundling这个大概念。还有一个问这两个strategy有什么不同。
还有一篇是firm和bank。第一段讲公司要管银行借钱去开发新项目。这个时候公司要证明自己有能力还钱，银行也需要考察公司有能力还钱。然后第二段讲银行要想调查公司是否有能力还钱就需要charge fee（这后面有一个括号讲为什么会charge fee 有一道题问这个fee）第三段讲说一些low-cost公司会通过apply一个东西来signal自己有能力还钱。第四段说however，必须要在high-cost的公司也apply这个东西的时候low-cost才能有效signal。
最后一篇讲的是political change和woman suffrage的关系。这篇是最后一篇再加上我不认识suffrage这个单词所以读的很晕。第一段讲什么记不太清了。题也没有怎么出在第一段。第一句话是人们认为political changes跟woman suffrage没什么关系。接下来好像是具体分析了一下为什么没有关系。第二段是一个让步段。（有一道题问第二段是什么作用）说有一些recent researcher（这个要出题 问提这些researchers的作用是什么）认为woman suffrage还是有一些作用的。下一句开始说有些new issues怎么怎么样 这里很难懂 而且出了题 问这些new issues到底是由什么造成的。
新补充一下作文 作文讲了一个国家 五年前举办了一个国际足球赛 之后三年来这个国家旅游的人变多了。于是这个国家现在决定再举办一个international sport event 这样就可以再次提升旅游业并且让这个国家的经济发展。

小鱼你可以

感谢分享！               

王大易

谢谢分享

小猪佩奇的表哥

感谢！！！数学第一题是e么

billyisfragile!

https://sloanreview.mit.edu/article/bundling-new-products-new-markets-low-risk/?article=bundling-new-products-new-markets-low-risk&post_type=article

Aggregation Bundling
This concept involves producing a bundle that will appeal to a number of customer segments. Suppose you have four items: A, B, C, and D. One segment strongly prefers the first three, and a second segment strongly prefers the last three. It may be possible to combine all four items into one bundle and price it so that both segments will purchase it, albeit for different reasons. That is, by bundling, you are combining segments of the market with different tastes and preferences into an aggregate segment with a similar valuation for the bundle. The goal is to attract a large market and reduce complexity by having fewer products. The secret is in pricing the bundle so that your comprehensive offering is more attractive than specialized bundles offered by competitors. A corollary of the basic strategy is to produce, in addition, special bundles (or individual items) for smaller market segments at higher prices.


Credit card firms use this strategy. The typical credit card includes a wide variety of services. It is unlikely that a large segment of subscribers actually are interested in all of these services. Customers who travel frequently may value car rental insurance or access to traveler's checks in foreign countries. Others may value a purchase protection plan. They all buy the same card.

billyisfragile!

数学记得ds有一道题讲的是一个大集合{1,2,3,4,5} A和B是这个大集合的两个子集，A^和B^分别代表A和B的非。问你A和B的交集是什么 给了两个条件 分别是A和B^的交集是{2}和A^和B的交集是{4}

https://forum.chasedream.com/thread-1313232-1-1.html

*DS: Set S={1,2,3,4,5,6} A, B 都是set S的子集，问能否求出A'∩B?
条件(1): A∩B={4}
条件(2): A∩B'={2}
这题我是选D, 抓了一下好像没办法确定A'∩B,会有两三种状况

【数讨君】
我猜 A'是 A 的补集的意思？
条件 1：A'没有4，B 有4，别的不知道，不充分
条件 2：A'没有2，B 也没有 2，所以不知道 A'和B 有啥
条件 1+2：只知道A'和B 没有 2，也不可能交4，别的 1356 都有出现的可能
比如 A={2,4}，B={3,4}时满足条件 A'∩B=3；A={2,4}，B={1,4}时满足条件 A'∩B=1


所以不充分，选E

kluivert

bzy! 发表于 2018-9-26 07:06
https://sloanreview.mit.edu/article/bundling-new-products-new-markets-low-risk/?article=bundling-new ...

我前面就发现个类似你这样的大神，最后都把原文找出来了
貌似下面是原文

http://bear.warrington.ufl.edu/weitz/mar7786/articles/bundling.pdf

billyisfragile!

是原文吗？

https://fraser.stlouisfed.org/files/docs/historical/frbphi/businessreview/frbphil_rev_2006q2.pdf
Michael Manove, Jorge Padilla, and Marco Pagano’s model illustrates what economists call the screening role of collateral. In their model, collateral helps the bank distinguish between firms that are likely to have positive net present value (NPV) projects and firms that are likely to have negative NPVprojects.

Suppose there are two types of firms: firms with high operating costs and firms with low operating costs. When a firm applies for a loan, it knows its operating cost, so it has an idea of whether its project is likely to be successful and have a positive NPV. But since there are other factors affecting the project’s success, the firm cannot know for sure. The bank can find out whether the firm has high costs or low costs as well as other information about the firm’s project, but only after some investigation. Before the bank investigates, all firms look identical to the bank.

To recoup the cost of evaluation the bank must charge some fee. To make sure it puts the appropriate amount of effort into evaluating the loan, the bank charges only those firms whose loans are approved. Otherwise, the bank can make money by charging a fee without doing an evaluation and then rejecting all applicants. In turn, firms whose loans are approved end up subsidizing the firms whose loans are not approved. But since the low-cost firms are the ones whose loans are more likely to be approved, they know they are the ones subsidizing the high-cost firms.

To avoid this, low-cost firms may try to distinguish themselves from high-cost ones by offering to post collateral. An economist would say that the low-cost firm is using collateral to signal its information to the bank. Posting collateral is costly to the firm because the firm loses it if its project fails. However, since the firm’s costs are low, it knows the project is very likely to succeed and the risk of losing collateral is not large.

However, low-cost firms can signal their information using collateral only if high-cost firms find it unprofitable to mimic low-cost firms by posting collateral, too. This is the case if the high- and low-cost firms differ enough. For a high-cost firm, the cost of putting up collateral is much higher than for a low-cost firm because the firm knows it is more likely to default. The result is that low-cost firms post collateral and high-cost firms do not.

The bank can then distinguish between the two firms. If a firm is willing to post collateral, the bank concludes that the firm has low costs and approves the firm’s project without an evaluation; in this case, a careful evaluation is not likely to change the bank’s decision. If a firm is not willing to post collateral, the bank concludes the firm has high costs and evaluates the project; in this case, the bank’s evaluation may indicate that the firm’s project has a positive NPV, even though the firm has high costs.

一本舒

感谢分享！               

duke182

bzy! 发表于 2018-9-26 07:13
https://forum.chasedream.com/thread-1313232-1-1.html

我演算的结果也是E 因为5是个不确定数 可以AB都含 也可以都不含 所以推不出唯一解