Testbook Test Series: Combinatory - Permutations And Combinations

Question

NUMBER OF WAYS IN WHICH CORNER OF THE SQUARE CAN BE COLORED WITH TWO COLORS. (ITS IS PERMISSIBLE TO USE A SINGLE COLOUR ON ALL FOUR CORNER)

Comments

If we consider unlabelled ... Than how 2 2 is  in 2 ways and 1 3 is in 1 way ?? Plz explain

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Oops! It is 16 not 18.

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If we consider the colors as 0 and 1. Then every corner can be assigned either 0 or 1. Therefore, answer is equal to the no. of binary strings with 4 0s or 1s which is equal to $2^{4}$