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All the arrangements, with or without meaning, of the word FARMER are written excluding any word that has two \mathrm{R}appearing together. The arrangements are listed serially in the alphabetic order as in the English dictionary. Then the serial number of the word FARMER in this list is____________
 

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Words starting with A and 2 R's are seperated \underline{A}\: \underline{E}\: \underline{F}\: \underline{M}\: \underline{R}\: \underline{R}= \frac{5!}{2!}-4!
                               = 60-24= 36

Such words starting with E = \underline{E}\: \underline{A}\; \underline{F}\; \underline{M}\: \underline{R}\; \underline{R}
                                             = 60-24= 36

Starting with F   =\underline{F}\: \underline{A}\: \underline{E}\: \underline{R}\: \underline{M}\: \underline{R}\:
                              \underline{F}\: \underline{A}\: \underline{M}\: \underline{R}\: \underline{E}\: \underline{R}\:
                              \underline{F}\: \underline{A}\: \underline{R}\: \underline{E}\: \underline{M}\: \underline{R}\:
                               \underline{F}\: \underline{A}\: \underline{R}\: \underline{E}\: \underline{R}\: \underline{M}\:
                               \underline{F}\: \underline{A}\: \underline{R}\: \underline{M}\: \underline{E}\: \underline{R}\:
so order = 36+36+5= 77

Posted by

Kuldeep Maurya

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