- A sum of money doubles itself at a certain compound interest rate in 10 years.
- We are asked to find how long it takes to become eight times the original value.
- Doubling means \(2^1\), so in 10 years, the amount becomes \(2 \times\).
- Eight times means \(2^3\), so it takes three doubling periods.
- Since one doubling period is 10 years, three periods would be \(3 \times 10 = 30\) years.

**✅Option: 2 - 30** is correct.

YOUR ANSWER IS RIGHT