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.