Permutations And Combinations Question 366
Question: If a denotes the number of permutations of x+2 things taken all at a time, b the number of permutations of x things taken 11 at a time and c the number of permutations of x -11 things taken all at a time such that $ a=182bc, $ then the value of x will be
Options:
A) 12
B) 10
C) 8
D) 6
Correct Answer: A $ \Rightarrow c=(x-11)!;a=182bc $ $ \therefore (x+2)!=182\frac{x!}{(x-11)!}(x-11)! $ $ \Rightarrow (x+2)(x+1)=182=14\times 13 $ $ \therefore x+1=13 $ $ \therefore x=12 $
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Answer:
Solution:
BETA
