4 seniors, 6 juniors, choose 3 as a group with at least 1 senior (answer 100)
我以为是C4(1)*C9(2)=144. 刚开始做数学,底子薄,请指教,谢谢
可以比较简单的考虑:
C10 3-C6 3=100
直接排除3个都是J的情况