这种题一般怎么做啊 总错 请各位指导 答案是C

woshishizhan

Q9:
If the average(arithmetic mean) of four different numbers is 30, how many of the numbers aregreater than 30?
(1)     None of the four numbers is greater than 60.
(2)     Two of the four numbers are 9 and 10,respectively.
                 
A. Statement (1) ALONEis sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONEis sufficient, but statement (1) alone is not sufficient.
C. BOTH statementsTOGETHER are sufficient, but NEITHER statement ALONE issufficient.
D. EACH statement ALONEis sufficient.
E. Statements (1) and (2)TOGETHER are NOT sufficient.

jennifer聂

用120－10－9＝101 再用101除以2 得到50。5   第3个数在没得前提条件下是可以大于30 和小于30的 只要最后一个数 足够大就是了 不能判断
如果选c 那么第3个数和第4个数就有限定 只能在60以内 所以 有2个 可以判断