prep中的一道题

今天刚模考了一把prep，有道逻辑题，虽然选对了，但是排除法做的。回头想搞搞明白。

Finging of a survey of SYSTEMS magazine subscribers:Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were palced by subscribers under age thirty-five.

Finging of a survey of advertisers of adbertisers in SYSTEMS magazine:Most of the merchandise orders placed in response to advertisements in SYSTENMs last year were placed by people under age thirty-five.

For both of the finding to bu accurate,which of the following must be ture?

正确答案是：last year many people who placed orders for merchandise in response to advertisements in SYSTEMS were not subscribers to the magazine.

因为其他选择不是在说over thirty-five就是在说去年和今年的比较，所以很好排除。

但是正确选择为什么对？老实说我对题目也只读懂了50％。

大家帮我看看，谢谢！

杂志订购者中同时订购了广告商品的30%为35岁以下的年轻人；

但广告商收到的订单中，35岁以下的占了大多数；这里可以看出有一个比例差异：从30%->大多数；那么这部分人既然不是来自杂志订购者，那么就应该是答案中所列情况。

不知对否。

终于搞明白了