急：向nn求助一道GWD的数学题：希望给出详细解释！

iloveandy · 发表于 2008-7-16 15:29:00

Q20:
                          Favorable          Unfavorable         Not Sure


Candidate M          40                       20                    40

Candidate N          30                       35                    35


The table above shows the results of a survey of 100 voters each responded “favorable” or “unfavorable” or “not sure” when asked about their impressions of candidate M and of candidate N. What was the number of voters who responded “favorable” for both candidates?

(1) The number of voters who did not respond “favorable” for either candidate was 40.

(2)   The number of voters who responded “unfavorable” for both candidates was 10.

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.

Answer: A

XYZLSH07 · 发表于 2008-7-16 16:12:00

voters who responded “favorable” + voters who dont' responded “favorable” = 100

voters who dont' responded “favorable”= voters who did not respond “favorable” for either candidate

所以（1） sufficient

of voters who responded “unfavorable” for both 只是 voters who did not respond “favorable” for either candidate 的一部分，仅知道它不能得出结论。

所以选A

急：向nn求助一道GWD的数学题：希望给出详细解释！