一道国外数学题Ten students have been nominatedfor the positions ofsecretary,treasurer,social convenor,and fundraising chair.In how many ways can these positions be filled if a pair of twins are running and plan to switch positions on occasion
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一道国外数学题Ten students have been nominatedfor the positions ofsecretary,treasurer,social convenor,and fundraising chair.In how many ways can these positions be filled if a pair of twins are running and plan to switch positions on occasion
一道国外数学题
Ten students have been nominatedfor the positions ofsecretary,treasurer,social convenor,and fundraising chair.In how many ways can these positions be filled if a pair of twins are running and plan to switch positions on occasion for fun since no one can tell them apart?
这个问题有高手能看懂并讲讲怎么做吗?
一道国外数学题Ten students have been nominatedfor the positions ofsecretary,treasurer,social convenor,and fundraising chair.In how many ways can these positions be filled if a pair of twins are running and plan to switch positions on occasion
就是说有10人被提名参加4个职位的选举,如果有个双胞胎在中间捣乱换来换去的话,这4个职位的排列有多少种方法?
10C4*2,就是 10!/((6!)*4*)*2 = 420 种方法