Question

设集合A={1,2,3,4,5,6,7,8,9,10},集合B是集合A的三元素子集,求集合B中至少有2个偶数的概率

Answer 1

C1,5*C2,5/C3,10

=5*(5*4)/(2*1)/[(10*9*8)/(3*2*1)]

=5*10*6/(10*9*8)

=5/12