The question asks for the interest rate per annum for an investment of Php 30,000 over 3 years, which grows to Php 48,000.

We can use the formula for simple interest or compound interest. Since the problem does not specify, we will assume simple interest.

Formula for Simple Interest:

$A = P(1 + rt)$ Where:

• $A$ is the total amount (Php 48,000)
• $P$ is the principal (Php 30,000)
• $r$ is the annual interest rate (unknown)
• $t$ is the time (3 years)

Rearranging the formula to solve for $r$: $A = P(1 + rt) \implies 1 + rt = \frac{A}{P} \implies rt = \frac{A}{P} - 1 \implies r = \frac{\frac{A}{P} - 1}{t}$

Substituting the known values: $r = \frac{\frac{48,000}{30,000} - 1}{3} = \frac{1.6 - 1}{3} = \frac{0.6}{3} = 0.2$

Thus, the interest rate per annum is 20%.

Would you like more details on this solution, or do you have any questions?

Related Questions:

1. How would the interest rate change if the time period were 5 years?
2. What would be the total amount after 3 years if the interest rate was 15% instead?
3. How is compound interest calculated, and would it yield a different interest rate in this case?
4. What are the key differences between simple and compound interest in financial calculations?
5. How much interest would you earn in 2 years instead of 3 at this same rate?

Tip:

When dealing with interest rate calculations, it's essential to know whether the interest is simple or compound, as they can lead to different outcomes. Always clarify if not given in a problem.