原帖由 prozzy 於 2007-5-18 23:05 發表。 
* S3 {) N1 F. g2 o$ athe answer is -$97 for sure.
0 H) R' P6 A$ S/ y% j公仔箱論壇Think about it this way 公仔箱論壇3 N) l5 w, l# S: Y3 ^: N
1) if the 100 bucks is not a fake one, the store owner will gain $3 ($21-$18)公仔箱論壇5 e0 O) I3 `' K3 b3 _4 d6 u* s
2) Now, the owner discovered that the 100 bucks is fake. You can th ... # [- P" s2 z2 Y9 \; C$ A( {& h- V$ }' s1 Q1 a. P. f
5.39.217.769 B& F2 Q! P1 k& C
1) very good, it the 100 bucks is real, your answer is correct, but it is fake, so your answer is wrong公仔箱論壇" r/ E" Z4 L" C6 ^# r( ?+ p
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think about it, when the bill is fake, and he gave him $79 change back, that is -79 already, it means the 100 on his hand is equal to 0 (Zero), how did he makes profit when he got a fake bills, then he need to pay another real 100 dollars bill to his neighbor, that another -100, plus the product he lost, thats another 18 dollars, Do Not Even Mention the 3 dollars, there is no profit he can make when he got a fake bill.公仔箱論壇7 j4 w+ h" P% b+ {( p7 m" e1 z C2 e
; c! Z, P3 ^) c2 {! iI know the answer becoz it really happening to my friend in his store in real LIFE, it can not be wrong. |