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标题: prep DS1 144 [打印本页]

作者: cateye    时间: 2010-1-29 14:14     标题: prep DS1 144

If $1,000 is deposited in a certain bank account and remains in the account along with any accumulated interest, the dollar amount of interest, I , earned by the deposit in the first n years is given by the formula I
=1000(1 + r/100)n - 1〕, where r percent is the annual interest rate paid by the bank.  Is the annual interest rate paid by the bank greater than 8 percent?

(1)  The deposit earns a total of $210 in interest in the first two years.

(2)  ( 1 +  r/100)2 > 1.15

我觉得2这个式子从理论上能够算出r的值,既然能够计算出r,那么就可以跟8比较大小啊,为什么答案是A呢,哪位大NN能帮忙解答一下啊





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