Single Choice

From $$6$$ different novels and $$3$$ different dictionaries, $$4$$ novels and $$1$$ dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangements is

AAt least $$500$$ but less than $$750$$
BAt least $$750$$ but less than $$1000$$
CAt least $$1000$$
Correct Answer
DLess than $$500$$

Solution

Number of novels =6
Also, the number of dictionaries =3

Number of ways of selecting 4 novels and 1 dictionary is 6C4×3C1

Arrangements such that the dictionary is always in the middle is given by :
NNDNN
The position of the dictionary is fixed. The novel can be arranged in 4! different ways

Total number of ways we can arrange 4 novels and 1 dictionary so that dictionary always in the middle

=6C4×4!×3C1

=15×24×3=1080

Option C is correct.


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