Posted by matt on Tuesday, July 15, 2008 at 3:30am.
there are 100 boys, 80 girls, and 20 teachers. In how many ways can a group of 5 (2 girls, 2 boys and a teacher) be selected?

maths  drwls, Tuesday, July 15, 2008 at 6:18am
[100!/(2!*98!)]*[80!/(78!)(2!)]*20
= [(100*99)/2][(80*79)/2)]*2
= 31,284,000