A squad of 20 boys, which includes 2 sets of twins , is available for selection for a cricket team of 11 players. Calculate the number of different teams that can be selected if one set of twins is selected but neither twin from the other set is selected.

Question

Is this a combination?

Answer 1

yes
first select one of the pairs of twins .... C(2,1) = 2
So in effect 2 players are chosen but 4 players are taken out of the picture, we need 9 more from the remaining 16 ----- C(16,9)

number of teams = 2*C(16,9) = ....