Find the rate at which a sum of money will become four times the original amount in 2 years, if the interest is compounded half-yearly.

Explanation

To find the rate at which a sum of money will become four times the original amount in 2 years with interest compounded half-yearly, we can follow these steps:

### Step 1: Understand the problem
We need to find the rate of interest (r) that will make the principal amount (P) grow to four times itself (4P) in 2 years when compounded half-yearly.

### Step 2: Identify the variables
- Let the principal amount be \( P \).
- After 2 years, the amount becomes \( 4P \).
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