急，一道宏观经济学题目。有图。请高手帮忙。

Question

Suppose the economy of Utopia has one bank,which has a reserve
ratio requirement of 10%.Below are three possible balance sheets of the bank.

For each balance sheet determine how a withdrawal of 1,000 affects
(1). the final supply of money in Utopia.
(2). the final reserves of the bank.
(3). the final excess reserves of the bank.
下图是三种情况balance sheet。请分别叙述对这三种情况的 final supply ，reserves，excess reserves的影响。

Answer 1

(a) cash reserve减小1000， deposit减小1000， loan不变。因为loan 不变，所以final supply不变。excess reserve减小1000， reserve不变。
(b) 开始时，cash reserve减小1000,但由于reserve requirement, 银行需要收回500的贷款，所以最终，cash reserve减小500， loan减小500，deposit减小1000。因为loan减小500，final supply减小500。之后reserve不变，excess reserve减小500。
（c) 开始时cash reserve减小1000，后来银行需要收回1000的贷款（原因用b), 所以最终cash reserve不变，loan减小1000。所以，final supply减小1000， reserve和excess reserve都不变。