Gwd-19-Q10:

If $1,000 will be deposited in a bank account and I is the dollar amount of interest earned from the original deposit, represented as I = 1000 {(1 + r/100)ⁿ – 1}, and the annual interest rate is r percent, is r > 8 percent?

(1) The deposit earns a total of $210 in interest in the first 2 years.

(2)    (1 + r/100)² > 1.15

答案为D，我选A。由（1）可得 r=10,由（2）可得r>7.3 。

有一道题实在没找到，恳请解答

Gwd-19-Q22:

A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter or a pair of distinct letters written in alphabetical order.  What is the least number of letters that can be used if there are 12 participants, and each participant is to receive a different code?   

A.   4

B.    5---答案

C.   6

D.   7

E.    8

我选的是A。我觉得关键在于对in alphabetical order的理解，恳请大家帮忙，谢谢

in alphabetical order的意思是按字母顺序吗？也就是ab和ba不一样的意思吧．这样的话４个就够了／关键还是不太确定in alphabetical order

in alphabetical order的意思是按字母顺序吗？也就是ab和ba不一样的意思吧．这样的话４个就够了／关键还是不太确定in alphabetical order

in alphabetical order的意思是按字母顺序吗？也就是ab和ba不一样的意思吧．这样的话４个就够了／关键还是不太确定in alphabetical order