4 professors and 6 students are being considered for membership on a supervisory committee which must consist of 2 people. If the committee has to include at least 2 professor, how many ways can this committee be formed?
Choose the correct choice from the following choices.
A) 36 B) 60 C) 72 D) 80 E) 64
you count up combinations twice.   4*9*8... and let me name 6 with students A,B,C,..,F   after choosing a professor, when you choose Student A and B, you can choose A first, then B. Or B first, then A. Both combination are same.   I don't think that's the only mistake.   64 is a factor of = 2^2*4^2   64 is a factor of = 2^4*2^2.   These are very different numbers and you cannot divide 64 with something to get to 64. ANS 64
<result>E</result>
4 professors and 6 students are being considered for membership on a supervisory committee which must consist of 2 people. If the committee has to include at least 2 professor, how many ways can this committee be formed?