Answer :
Given: 2nC3: nC3 = 12 : 1
To find: n=?
2nC3: nC3 = 12 : 1
⇒
⇒
⇒
⇒
⇒
⇒
⇒
⇒2n-1=3(n-2)
⇒2n-1=3n-6
⇒n=6-1=5
Ans:n=5
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