新PP test2

[stwang]

DS:set S consists of 20 different positive integers. How many of the integers in S are odd??
(1)10 of the integers in S are even
(2)10 of the integers in S are multiples of 4

正確答案是A
可是我覺得是E耶
set裡面一定是連續的整數嗎
不能一個set裡面是{2,4,6,8,10,...20}嗎??
請教各位大大 這題A何解呢??

[zazer.lin]

DS:set S consists of 20 different positive integers. How many of the integers in S are old??
(1)10 of the integers in S are even
(2)10 of the integers in S are multiples of 4

正確答案是A
可是我覺得是E耶
set裡面一定是連續的整數嗎
不能一個set裡面是{2,4,6,8,10,...20}嗎??
請教各位大大 這題A何解呢??

小弟猜想...題目應該是問How many of the integers in S are odd

一個set裡的element不一定要是連續的整數,element可以為任何的型態.

statement(1)說S裡面有10個elements是偶數
題目的第一句話是說
set S consists of 20 different positive integers
這句話已經表明了S裡的element都是正整數了...
在ets的觀念裡...整數只有兩種型態...even or odd
所以另外10個一定是odd囉....

[stwang]

呵 我打字打錯了啦 是odd才對

經你這麼一說 我了解了
因為(1)說是10個偶數
所以set裡面不可能是{2,4,6,8,10....40}

那就一定是10個奇數 10個偶數了
謝謝zazer.lin大大的講解