This question was previously asked in

GSET Official Paper 2: Held on September 2018

Option 4 : 5

Simplification

5070

15 Questions
15 Marks
15 Mins

**Given**:

2nCn-1 : (2n - 1) Cn = 5 : 3

**Formula Used**:

^{n}C_{r} = n!/r!(n - r)!

**Calculation**:

⇒ 2n × (2n - 1)!/(2n - n + 1)!(n - 1)!]/(2n - 1)!/(2n - 1 - n)!n! = 5/3

⇒ 2n × (n - 1)! × n!/(n + 1)!(n - 1)! = 5/3

⇒ 2n/(n + 1) = 5/3

⇒ 6n = 5n + 5

⇒ n = 5

∴ Required value of n = 5