GWD13Q8(PS)

由 **kikisky** » 2004-11-01 20:18

對不起~我不知道要貼題目XD
如下
請各位大大幫忙囉

At a certain food stand, the price of each apple is cent 40 and the price of each orange is cent 60. Mary selects a total of 10 apples and oranges from the food stand, and the average (arithmetic mean) price of the 10 pieces of fruit is cent 56. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is cent 52?

A.1
B.2
C.3
D.4
E.5

請問這題~怎麼算出答案(E)5的??
我算來算去都是(B)2ㄟ...... ^o)

由 **kikisky** » 2004-11-02 00:36

對不起~我不知道要貼題目XD
如下
請各位大大幫忙囉

At a certain food stand, the price of each apple is cent 40 and the price of each orange is cent 60. Mary selects a total of 10 apples and oranges from the food stand, and the average (arithmetic mean) price of the 10 pieces of fruit is cent 56. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is cent 52?

A.1
B.2
C.3
D.4
E.5

由 **huacy** » 2004-11-02 00:45

放回後的總個數並不是 10 個 ;)

放回二個平均是 55
放回五個平均是 52

由 **kikisky** » 2004-11-02 00:49

啊~~原來~~是我豬頭~XD
謝謝你^ ^

由 **汪汪北鼻** » 2004-11-02 00:57

A=apple, O=orange
1.A+o=10
2.40A+60O/10=56

設拿走x個
求40A+60(O-X)/A+(O-X) =52

得X=5 ;)

由 **kikisky** » 2004-11-02 01:01

厲害~~謝謝相助^ ^

由 **blacklilu** » 2004-12-15 23:11

我真是太粗心了....果然是強

由 **uioxcv** » 2005-10-24 20:53

一開始apple有X個, 40X+60(10-X)=560 -->X=2,ORANGE=8

設第二次剩下Y個橘子.APPLE不變仍然是兩個
40*2+60Y=52(2+Y) -->Y=3
so橘子減少了8-3=5個

GWD13Q8(PS)

GWD13Q8(PS)

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