Correct Answer - Option 1 : 9 years

**FORMULA USED:**

Simple Interest = PRT/100

Where, P = principle, R = Rate of interest, T = time period

**CALCULATION:**

According to the question

(10000 × 4 × T)/100 = (12000 × 6 × 5)/100

⇒ T = 360000/40000 = 9

**∴ The required time = 9 years**