求教GWD1--19

huskygal

Q19:

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.

谢谢各位大侠~~！！

karen_gao

假设$60,000 以x%计算年利率的部分为a，则以y%计算年利率的部分则为：60,000-a。

所以，根据题意，ax%+（60,000-a）y%=4080.

根据(1)     x = (3/4) y，

根据(2)    a：(60,000-a)=3:2

所以，解方程应该可以得出x的值。答案C

legendends

AX+BY=4080;A+B=60000.

如果X不=Y,要求出上述方程的值需要＋2条件。

1、条件是 x = (3/4) y，无解，求不出。

2、条件是A/B=3/2,单独此条件，也无解。

3、如果条件1＋条件2，可求出36000X＋4/3×24000X＝4080，X＝6％，有解。

故应该选C啊。

huskygal

谢谢！！感激涕零！！