The letter of the word LABOUR are permuted in all possible ways and the words thus formed are arranged as in a dictionary. What is the rank of the word LABOUR?
A. 242
B. 240
C. 251
D. 275
Answer: Option A
Solution(By Examveda Team)
The order of each letter in the dictionary is ABLORU. Now, with A in the beginning, the remaining letters can be permuted in 5! ways. Similarly, with B in the beginning, the remaining letters can be permuted in 5! ways. With L in the beginning, the first word will be LABORU, the second will be LABOUR. Hence, the rank of the word LABOUR is, 5! + 5! + 2 = 120 + 120 + 2 = 242 Note: 5! = 5 × 4 × 3 × 2 × 1 = 120This Question Belongs to Arithmetic Ability >> Permutation And Combination
Join The Discussion
Comments ( 2 )
Related Questions on Permutation and Combination
A. 3! 4! 8! 4!
B. 3! 8!
C. 4! 4!
D. 8! 4! 4!
A. 7560,60,1680
B. 7890,120,650
C. 7650,200,4444
D. None of these
A. 8 × 9!
B. 8 × 8!
C. 7 × 9!
D. 9 × 8!
3 1 2 4 6 5 (RANKING)
L A B O U R (WORD)
2 0 0 0 1 0 (TRICK U SHOULD CONCLUDE WHAT IS HAPPENING,,,,i.e.for'L' it is no of ranks which r less
than rank of 'L')
X X X X X X
5! 4! 3! 2! 1! 0!
......................................
2 X 5!+1
Why a & b only can bigining words.
Why only 2 time factorial given.
Why only two modification do in lastly.