ChaseDream

标题: TTGWD11-13 [打印本页]

作者: amyding85 时间: 2006-9-6 18:11
标题: TTGWD11-13

Q13:

On a certain day, Tim invested $1,000 at 10 percent annual interest, compounded annually, and Lana invested $2,000 at 5 percent annual interest, compounded annually. The total amount of interest earned by Tim’s investment in the first 2 years was how much greater than the total amount of interest earned by Lana’s investment in the first 2 years?

A. $5

B. $15

C. $50

D. $100

E. $105

Answer: A算了N遍还是得105，

能不能帮着算一下啊？我那里错了？1000*（1+0。1）^2-1000-2000*(1+0.05^2)

作者: jenny22 时间: 2006-9-6 18:36
should be 1000*（1+0。1）^2-1000 减去2000*(1+0.05)^2-2000

作者: ruopuli 时间: 2007-4-17 12:40

First year's earning for Tim are: 1000*0.1=100

second year's earing for Tim are: (1000+100)*0.1=110

So two year's total earning are 100+110=210

First year's earning for Lana are: 2000*0.05=100

Second year's earing for Lana are (2000+100)*0.05=105

total earning for Lana are 205

The difference between Tim and Lana are 210-205=5

作者: 双鱼游 时间: 2010-9-24 15:52
楼主错在题目要求的是The total amount of interest，利息，而不是本金加上利息，S＝P（1＋i）^n这个公式算的是本息和，所以应该再减去本金，也就是1楼说的

欢迎光临 ChaseDream (https://forum.chasedream.com/)