2. How many triangles can be obtained by joining 12 points, five of which are collinear?
3. There are 10 points in a plane, no three of which are in the same straight line excepting 4 points which are collinear. Find the number of straight lines obtained from pairs of these points.
4.How many different selection of 4 books can be made from 10 different books?
5. From a group of 15 cricket players, a team of 11 players is to be chosen. In how many ways this can be done?
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