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TPJC 2015 prelims, qn 8aii, Permutations and combinations(PnC)
Photo of the qn can be found here : https://www.dropbox.com/s/d8bs0b68m9k63kn/20160823_211241-1-1.jpg?dl=0
solution : 10c3 x 7! / (3!x2!)
Qn : how is it so certain that the order of A,E,U will be in that order when we apply 10 choose 3 ? wouldn't the order be jumbled up, for example, E,A,U or U,E,A?
Answer : You can be certain it would be A,E,U when you apply 10 choose 3. to get other orders, e.g. E,A,U, you'll have to permute the letters, i.e. 10c3 x 3!