Correct Answer - Option 1 : 7%

**Given:**

7000 invested for first 3 years

After 3 years 3000 more invested

Total interest after 8 years = 4970

**Formula used:**

Simple interest = (Principal × Rate × Time)/100

**Calculation:**

Let the rate of interest be R% per annum

So according to question,

(7000 × R × 3)/100 + (10000 × R × 5)/100 = 4970

⇒ 210R + 500R = 4970

⇒ 710R = 4970

⇒ R = 7%

∴ Rate of interest = 7%