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2-172.      

Nathan took out a student loan for $1,200 at 10 percent annual interest, compounded annually.  If he did not repay any of the loan or interest during the first 3 years, which of the following is closest to the amount of interest that he owed for the 3 years?

(A) $360

(B) $390

(C) $400

(D) $410

(E) $420

答案是C

答案是C

有請NN們幫忙回答兩個盲點，感激不盡

有請NN們幫忙回答兩個盲點，感激不盡

1.為什麼我用複利公式算 利息=本金( (1+利率)^期數 - 1 )

1.為什麼我用複利公式算 利息=本金( (1+利率)^期數 - 1 )

  算出來會是14772 越算越大呀? 

  算出來會是14772 越算越大呀? 

2為什麼要用 1200*0.1+(1200+120)*0.1+(1320+132)*0.1的呢?

2為什麼要用 1200*0.1+(1200+120)*0.1+(1320+132)*0.1的呢?

因为只要求利息就可以了，你的式子里本金也滚了3次，但你最后只减了一个本金。

1200*[（1+0.1）^3-1]=1200*0.331=397.2约为400

ㄚ，打太急了，都沒看清楚PP題 打成 jj 題 了，已經改了，你提醒我，真不好意思

感謝樓上樓下的好心NN提供解答 ^  _____________________  ^