05 Past Paper (12) MATHS [復制鏈接]

12. Peter sold two flats for $999999 each. He lost 10% on one and gained 10% on the other. After the two transactions.Peter
A. gained $ 10101
B. gained $ 20202
C. Lost $ 10101
D. Lost $ 20202
THX.............................
ANs係D
但係點解

哦...呢條係有trick的
我都比佢fake左一開始...

題目話叫將兩座數都賣999999....一座就賺左10%...一座蝕10%
咁我將呢兩座樓let做x樓同y樓
formula: 0.9x=999999
        1.1y=999999

咁我地可以計到x係1111110,y係909090
x+y就係佢原來兩座樓應該賣到既價錢...即係2020200
依家佢只係賣到999999+999999=1999998
要計到賺定蝕~>-1999998-2020200=-20202
即係lost左20202蚊

明未...唔明舉手

當果2個flat既原價係x同y

1.1x=999999
0.9y=999999

x+y=2020200

所以net profit=999999+999999-2020200=-20202
所以係D

明哂;;;;;唔該