Correct Answer - Option 1 : 23 : 25

**Calculation:**

Here the first two-year interest rate of 8% and then 10%.

⇒ After 5 years = P × (8/100) × 2 + P × (10/100) × 3 = 0.16P + 0.3P = 0.46P

**Investment is for 7 years. **

**∴ last 5 years interest amount ⇒ the interest amount received form year 3 to year 7.**

⇒ Interest = P × (10/100) × 5 = 0.5P

**Ratio is 0.46P : 0.5P ⇒ 23 : 25**

If the interest amount changing after some time, you cant apply the standard equation straight away. Find the interest by splitting into periods where the interest rate is the same is throughout the period.

Here you can take the principal amount as P or 100.BUt if there are related questions it is better to take investment as P.