Question

# The total number of 4 letter words that can be formed from the string "AABBBBCC" is56486863

Solution

## The correct option is D 63Available letters :A,B,C Here following patterns are possible:   1.  XXXX   (all four letters are same) only BBBB, so only 1 way. 2.  XXYY   (two same and remaining two are also same) = 3C2×4!2!2!=18 ways. 3.  XXYZ (two same and remaining two are different) = 3C1×4!2!=36 ways 4.  XXXY (three same and remaining one is different) = 2C1×4!3!=8 Now, required number of ways : =1+18+36+8=63

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