(1) Xiao Zhang just got elected, so we have to choose two of the other seven, among which c72 = (7 * 6)/(2 *1) = 21,and the probability = 2156 = 3/8.
(2) Xiao Zhang and Xiao Li should be selected together, and the other six should be selected 1, C6 1=6/ 1=6, and the probability =6/56=3/28.
(3) Xiao Zhang and Xiao Li were not elected, so we should choose three of the other six, C63=(6*5*4)/(3*2* 1)=20, and the probability =20/56=5/ 14.
2. The algorithm is the same as above. First, calculate all the selection methods: c105 = (10 * 9 * 8 * 7 * 6)/(5 * 4 * 3 * 2 *1) = 252.
(1) on Party A and Party B, the remaining 8 are 3, C83=(8*7*6)/(3*2* 1)=56, and the probability =56/252.
(2) Party A and Party B did not attend, and the other eight were selected as 5, C85 = (8 * 7 * 6 * 5 * 4)/(5 * 4 * 3 * 2 *1) = 56, with a probability of 56/252.
(3) A goes up but B doesn't, 8 is 4, C84 = (8 * 7 * 6 * 5)/(4 * 3 * 2 *1) = 70, and the probability =70/252.
I forgot, it should be like this.