GWD数学题一道求解啊

xiaoxinxin

Q26:

K is a set of integers such that if the integer r is in K, then r + 1 is also in K.  Is 100 in K?

(1)     50 is in K.

(2)     150 is in K.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

why is a?

shelleyzhdai

如果150是r1的话，整个数列就不可能比150小了。r2=151,r3=153...

MerisaLees

這題我是這樣想的~~因為他給的是r+1~r=50  r+1=51.........

所以你只有辦法用低於100的數字去證明100在這個SET裡面!!

R=150的話~R+1=151.....已經超過100~故沒辦法證明

shelleyzhdai

楼上的牛牛啊，如果这题改成10个人，还是按那个规律排2排，答案是多少呢？

难道还是列举吗？有没有什么公式 或者规律？

xiaoxinxin

但 50 is in K.不一定能保证100在内吧？只是确定51在里面吧，然后再向后推？