问题如下：
Assume quantity theory of money holds, based on the following information, velocity of the money supply is:
选项：
A.60
B.7.5
C.900.
解释：
B is correct.
In quantity theory of money, Money supply ×velocity= price ×real output=nominal GDP. Substitute the information, ($2.0 trillion)(V)=$15.0 trillion. V= 7.5
考点：货币数量论
解析：根据货币数量理论,货币供应价×流通速率=实际产出×价格=名义GDP。代入数据得，($2.0万亿)(V)=$15.0万亿。V = 7.5
老师 题目中的 prices index 是什么？
