问题如下：
Which of the following statements about the capital conservation buffer are TRUE?
I. It is meant to protect banks in times of financial distress.
II. It means that in normal times a bank should have a minimum 7% Tier 1 equity capital ratio, total capital must be 10.5% of risk-weighted assets in normal periods.
III. It can be set between 0.0% and 2.5% of risk-weighted assets by the regulators in individual countries.
选项：
A.only I.
B.only II.
C.I and II.
D.I, II and III.
解释：
C is correct.
考点：the capital conservation buffer
解析：
The capital conservation buffer旨在金融危机时保护银行, I 正确。
正常情况下，对于Tier 1 equity capital，银行必须建立2.5%的buffer来cover银行在金融危机时的损失，即在正常情况下，Tier 1 equity capital的最低要求为7%（4.5%+2.5%=7%），total Tier 1 capital为8.5%，Tier 1和Tier 2为10.5%。II 正确。
The capital conservation buffer是监管要求，不是由各国的监管机构自行决定的，III 错误。
请问 total tier 1capital 为8.5%，怎么计算出来的呢？
