问几道 gwd数学

数学本来就不好,外加好几道意思都没看懂,大家帮忙看一下吧谢啦!

gwd 2

Q18:

On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship.  If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship’s passengers held round-trip tickets?

A.     33 1/3%

B.     40%

C.     50%

D.     60%

E.      66 2/3%

选c 关键没看明白怎么回事

gwd1

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.

c  ,也是意思搞不大懂

the first question

２０％的人是有来回票并有车。其中６０％有来会票的人是无车的，因此４０％有来会票的人是有车的，如设全体乘客是a,有来回票的人是b,  20%a=40%b   ==> b/a=50%

The second question

assume the money whose interet is X% is A and the money whose interet is Y% is B. then we can get :

A+B=60000

X%=(3/4)Y%

A:B=3:2

AX%+BY%=4080

then we can get the answer. so BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient

"the first question

20% of all passengers held round tickets with cars. ."

how to get the answer??

根据条件１和２可列出

A+B=60000

X%=(3/4)Y%

A:B=3:2

AX%+BY%=4080

４个方程，因此可求出X,so BOTH statements TOGETHER are sufficient,

非常感谢! 理解了!