If 2 different representatives are to be selected at random from a group of 10 employees, and if P is the probability that both representatives selected will be women, is P >1/2? (1) more than 1/2 of the ten employees are women (2) the probability that both representatives selected will be men is less than 1/10
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
1.设女性员工人数为n，当n取6时，则p=(6/10)*（5/9）=1/3<1/2;而若取n=9，同理可以得出n=4/5>1/2，so statement 1 alone is not sufficient;
2.对于statement2,P(2男)<0.1，只能得出P（2女）+P（1男1女）>0.9, so statement 2 alone is not sufficient;
3.仍设女性员工人数为n，由statement2 可知：[(10-n)/10]*[(9-n)/9]<1/10,化简可得：（10-n)*(9-n)<9,又因为n>5,所以n可以取7,8,9,10,当n=7时，p=(7/10)*(6/9)=7/15<1/2,而当n取8,9,10 时，p>1/2，so Statements (1) and (2) TOGETHER are NOT sufficient
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2010-5-23 16:15:12
收藏
收藏
楼主