Correct Answer - Option 2 : Between 8 and 9

**Calculation:**

Amount after T years =Prinicpal + Simple interest = 2 × Principal

Simple interest after T years = Principal

P × R × T/100 = P

T = 100/11.5 = 1000/115 = 8.69

**∴ The time by which the amount will double itself is between 8 and 9 years.**