A store purchased 20 coats that each cost an equal amount and then sold each of the 20 coats at an equal price. What was the store's gross profit on the 20 coats?
(1) If the selling price per coat had been twice as much, the store's gross profit on the 20 coats would have been $2,400.
(2) If the selling price per coat had been $2 more, the store's gross profit on the 20 coats would have been $440.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
关键:虚拟语气
(1) 是不充分的。设进价为每件$x,售价为每件$y,题目要求20(y-x)。(1) 只说了20*(2y-x)=2400,只能求出2y-x,求不出y-x。
(2) 是充分的。(2) 的意思是20*((y+2)-x)=440,那么20*(y-x)当然就是$400了。
条件二得200(x+2-y)=440直接求出profit
看清楚要求啥
题目C和P都是未知数
(1):如果S=2c,代入20*(S-C),得到该条件下的总利润=20*(2c-c)=2400,这里必须把S替换成2c,因为2400是在S=2c下才成立的利润,而非真正的s/c。
(2):如果S=s+2,代入20*(S-C),得到该条件下的总利润=20*(s+2-c)=440,这里能得出20(s-c)=400
条件二得200(x+2-y)=440直接求出profit
看清楚要求啥
而条件1中
g=p-c=440-400
条件2:SP+2-C=440/20
推出SP-C=20
20*20=400