[問題]GWD21-20

[magic]

Q20:
Of the 60 animals on a certain farm, 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.
答案是C

請大大們指點一下

[iven9]

Q20:
Of the 60 animals on a certain farm, 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.
答案是C

請大大們指點一下

這題題目有問題，原本題目似乎應該是Of the 60 animals on a certain farm, "2/3" are either pigs or cows. How many of the animals are cows?
沒有這個數字解釋就變了。
總之，如果改為這樣，那麼本題意思就是：
一個農場裡面有60隻動物，其中2/3是牛或是豬，問有多少頭牛？
(1)牛比豬多兩倍。
(2)最少有12頭豬(不可以等於12)。
由條件(1)可得知，在40隻動物之中，牛應該至少也佔2/3的比率，也就是應該最少是26.667頭，而豬應該最多是13.333頭，由於"活的"動物必須取整數，所以條件(1)不充分；但是加上條件(2)，就可以得知豬是13頭，牛是27頭，故充分。
所以答案選(C)。
請指教。

[magic]

不好意思阿
我題目少打ㄌ2/3