求教GWD31数学第一部分一道题

grande_ecole

A total of $60,000 was invested for one year.  But of this amount earned simple annual interest at the rate of x percent per year, and the rest earned simple annual interest at the rate of y percent per year.  If the total interest earned by the $60,000 for that year was $4,080, what is the value of x?

(1)     x = (3/4) y

(2)   The ratio of the amount that earned interest at the rate of x percent per year to the amount that earned interest at the rate of y percent per year was 3 to 2.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer:C

这道题我死活看不明白, 请路过的朋友帮忙解释一下, 咳,数学理解还是个问题

grande_ecole

是不是这道题太简单了, NN都不理哦,

希望大侠赶快出现吧

sammy生米

这题以前都有讨论过，自己搜索下啦，关键词：1-19

grande_ecole

谢谢MM的回答, 可我没找到, 我查了一下GWD的数学讨论,大概是xy-13的第19题, 不知道GWD31套的数学讨论在哪呢, MM或者路过的朋友告诉我一下链接, 多谢

xt142

$60,000分成两部分投资（设成A部分和B部分），A部分投资的利率是x，B部分投资的利率是y，总获利是$4,080，求x？

方程1：A*x+B*y=4080

方程2：A+B=60000

一共四个未知数，还需要两个方程才能解出x，所以条件(1)和条件(2)必须同时成立，x才有唯一解。

grande_ecole

谢谢楼上的啊,果然茅塞顿开哦, 其实题不难,怎么理解这么难哦,

好人好运哦!!!

xiaoy791

A total of $60,000 was invested for one year.  But (some) of this amount