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Question

Mathematics Question on permutations and combinations

If all the words with or without meaning made using all the letters of the word "NAGPUR" are arranged as in a dictionary, then the word at 315th position in this arrangement is

A

NRAGUP

B

NRAGPU

C

NRAPGU

D

NRAPUG

Answer

NRAPGU

Explanation

Solution

Arranging the letters in alphabetical order: NAGPUR

Starting with AA: 5!=1205! = 120 positions

Starting with GG: 5!=1205! = 120 positions, cumulative: 240

Starting with NN and AA: 4!=244! = 24 positions, cumulative: 264

Starting with NN and GG: 4!=244! = 24 positions, cumulative: 288

Starting with NN and PP: 4!=244! = 24 positions, cumulative: 312

Now, starting with NN, RR, and AA:

NRAGUP=1, cumulative: 313\text{NRAGUP} = 1, \text{ cumulative: 313}

NRAGPU=1, cumulative: 314\text{NRAGPU} = 1, \text{ cumulative: 314}

NRAPGU=1, cumulative: 315\text{NRAPGU} = 1, \text{ cumulative: 315}

Thus, the word at the 315th315^{\text{th}} position is NRAPGU.