[求助]prep上的数学

celery28

DS:If 500 is the multiple of 100 that is closest to x and 400 is the multiple of 100 that is closest to y,which multiple of 100 is closest to x+y?

1>   x<500

2>    y<400

题目看不懂 哪位帮个忙 谢谢

celery28

answer: E

celery28

自己up

aj_goodnews

450 < x < 550
350 < y < 450

(1) 450 < x < 500 --- Clearly INSUFF
(2) 350 < y < 400 --- Clearly INSUFF

(1)+(2) =>
800 < x+y < 900

If x+y is 820, the closest multiple of 100 would be 800
Else if x+y is 880, the closest multiple of 100 would be 900

So, INSUFF, hence E

aj_goodnews

Qn says "500 is a multiple of 100 that is closest to x" ...
-> if x were 420, the closest multiple of 100 would have been 400
-> if x were 560, the closest multiple of 100 would have been 600

So, the correct range of x values as per the qn stem is 450 < x < 550 ...

celery28

其实题应该会做，只是看不懂题目

谢谢aj，但是还是用英语写的，所以还是看不懂