prep2-76

rock19840717

Over a certain time period, did the number of shares of stock in Ruth's portfolio increase?
 
(1) Over the time period, the ratio of the number of shares of stock to the total number of shares of stocks and bonds in
Ruth's portfolio increased.
 
(2) Over the time period, the total number of shares of stocks and bonds in Ruth's portfolio increased.

请教这一题为啥答案是C啊，我觉得应该是无法确认的吧

wawadream

单独没法确认。

if the number of the stock and the bond is x, y

from 1) x/(x+y) increased

from 2) x+y increase

combined 1 and 2, x must increase.

sniperbill

恩，支持楼上的，你看哦，x/(x+y)变大了，同时分母也变大了，如果分子不变大的话就不会成立了