Correct Answer - Option 2 : 6.83%

**Given- **

Ratio of principal and amount after 13 years = 9 :17

Ratio of principal and amount after 14.3 years = 15 : 43.

**Concept Used-**

Simple Interest = P × R × T/100 [where P = Principal, R = Rate, T = Time]

**Calculation- **

Let the Principal be 9x and Amount be 17x and R = Rate of Interest

Interest = 17x - 9x

⇒ 8x

According to Condition-

8x = 9x × R × 13/100

⇒ R=100 × 8x/9x × 13

⇒ R = 800/117

⇒ 6.83%

∴ Rate of Simple Interest is 6.83%