问两道GWD的数学题

brunhildS

Q21:
A toy store’s gross profit on a computer game was 10 percent of the cost of the game.If the store increased the selling price of the game from $44 to $46 and the cost of the game remained the same, then the store’s gross profit on the game after the price increase was what percent of the cost of the game?


A.10.5%
B.11%
C.12.5%
D.13%
E.15%（答案是E，我怎么觉得缺数字啊）
Q22:
Four extra-large sandwiches of exactly the same size were ordered for m students, where m > 4.Three of the sandwiches were evenly divided among the students.Since 4 students did not want any of the fourth sandwich, it was evenly divided among the remaining students.If Carol ate one piece from each of the four sandwiches, the amount of sandwich that she ate would be what fraction of a whole extra-large sandwich? 答案是（4m-12）/(m(m-4))完全不知道是怎么来的，请人指导一下～谢谢啦

yoyo9012

Q21:

因为原售价为$44，利润率为10%，能算得成本为$40，因此现在的利润率为（46-40）/40=15%。

Q22:

3块sandwiche由m个人来分，剩下的那1块由（m-4）个人来分，而Carol每块都要了一份，所以总共为3/m+1/(m-4)=(4m-12)/(m(m-4))。

brunhildS

了解了，谢谢～

lilingfeng

第一题 设成本x, 那么利润就为0.1x,销售价就是1.1x，从“the store increased the selling price of the game from $44 to $46”得出1.1x=44 ,x=40
由于成本不变，增加后的利润为46-40=6，根据问题解得6/40=0.15 即E

第二题 设每份sandwich为k(因为same  size么），总共m个人，C同学四份每份都吃到，前三份吃的总量表示为3k/m（k/m + k/m + k/m,每份吃的量都相等），第四份吃的量表示为k/(m-4)  （有4个人不吃第四份),所以得到(3k/m + k/m-4 ) / k =4m-12）/(m(m-4） 即答案撒