求救！！Prep 2道数学题！ 谢谢！

mudiduanger

1.DS:  is the thre-digit number n<=550
条件1. the product of the digits in n is 30
条件2.  the sum of digit in n is 10

答案是C， 我的算法是条件1推出：xyz=30  2推出：x+y+z=10  但我觉得1、2推不出 100x+10y+z<=550.




2. Bobby bought two share of stock, which sold for 96 each.   If he had profit of 20% on the sale of the shares but a loss of 20% on the sale of the other share, then on the sale of both shares combined b bobby had.

答案是   the loss of 8,        我选的是 no loss, no profit.  我知道我选的错了，可是就是算不出the loss of 8.



大家帮帮忙吧！！！谢谢！！！

MarilynR

第一题
条件一可得 三个数字为 1，5，6 或者 2，5，3 ，不充分
条件二 单独不充分 两者结合可得 三个数字为 2，5，3， 任意组合 《=550

第二题能不能把原题 原样子打出来？

wangliming

two share of stock......share应该有s吧

jingjane222

第２题

0.96=1.2*X1  X1=0.8 (Share 1 with 20% gain)
0.96=0.8*X2  X2=1.2 (Share 2 with 20% loss)

X1+X2=2.00 (original price paid)
0.96*2=1.92 (price sold)

Loss 应该是 8 cents or 4%

mudiduanger

谢谢大家解答，明白了！！祝好运！