Mark the correct alternative in the following:
If in a group of n distinct objects, the number of arrangements of 4 objects is 12 times the number of arrangements of 2 objects, then the number of objects is
In a group of n distinct objects, the number of arrangements of 4 objects is = nP4 and the number of arrangements of 2 objects is = nP2.
According to the given problem,
⇒n×(n-1)×(n-2)×(n-3)=12×n×(n-1)
⇒(n-2)×(n-3)=12=(6-2)(6-3)
⇒n=6
Hence, the number of objects = 6.
[Note: 
nP4 and 
nP2]
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