GMATPrep一題，請幫幫忙，謝謝

[eureka]

of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows.
1. The farm has more than twice as many cows as it has.
2.the farm has more than 12 pigs.

answer:c

[HHC]

第1條件讀起來不太順，有沒有漏寫什麼字？

[sweetymanman]

題目沒有問題，不知道有人可以幫忙解嗎？

[scujean]

cd's題目

Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?
(1) the farm has more than twice as many cows as it has pigs.
(2) The farm has more than 12 pigs
Key: C

由1：c>2*p
cd'ans
一共40只豬，或者牛，這一點沒有問題。條件1說牛比豬的兩倍還多，條件2說，豬多於12只，那麽結合一下條件1，2和已知條件，就得出豬是13只，牛是27只。

[sweetymanman]

thanks

我重新把式子再列一次：

Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?
(1) the farm has more than twice as many cows as it has pigs. ---> c>2*p
(2) The farm has more than 12 pigs ---> p>12Key: C

題目：C+p=60 (60*2/3=40)
(1) c> 2*P
(2) p>12
所以p取最小為13, c>2p=26, c最小為27, 剛好C+P =40
若所以p取14, c>2p=28, c最小為29, C+P >40
所以（1)+(2)只有一解： p=13, c=27

cd'ans
一共40只豬，或者牛，這一點沒有問題。條件1說牛比豬的兩倍還多，條件2說，豬多於12只，那麽結合一下條件1，2和已知條件，就得出豬是13只，牛是27只。

[/quote]

[scujean]

辛苦了