tongxun

1、in the question there is no condition to illustrate how many people are in there。so we suppose that there be 10 teachers。
2、condition 1）the number of female teachers is 6：
6/10 *5/9 =1/3 less than 1/2。however， if there are 9 female teachers：
9/10 *8/9 =4/5 more than 1/2。
therefore， this condition is insufficient。
3、condition 2） x/ 10 *（x-1）/9 《 1/10 =》x（x-1）《9
=》x=1，2 or 3
such means that the number of female teachers would be 9，8，or 7
7/10 *6/9 =7/15 less than 1/2
9/10 * 8/9 more than 1/2
therefore， this condition is insufficient too。
referring the condiotion 2， although the number of female teachers is 7，which is more than 5，we cannot confirm whether 俩个都是女老师的概率>1/2吗？
I choose E。