Compound Interest Period
1. **Stating the problem:** We need to find the time period (in years) for which Rs. 30,000 amount at 7% per annum compound interest becomes Rs. 30,000 + Rs. 4347 = Rs. 34,347.
2. **Formula for compound interest:** The amount $A$ after $t$ years at rate $r$ per annum compounded annually on principal $P$ is given by:
$$ A = P (1 + \frac{r}{100})^t $$
3. **Given values:**
- Principal $P = 30000$
- Rate $r = 7$%
- Amount $A = 30000 + 4347 = 34347$
4. **Substitute into the formula:**
$$ 34347 = 30000 \times \left(1 + \frac{7}{100}\right)^t = 30000 \times (1.07)^t $$
5. **Solve for $t$:**
\[ (1.07)^t = \frac{34347}{30000} = 1.1449 \]
6. **Take natural logarithm on both sides:**
$$ t \ln(1.07) = \ln(1.1449) $$
7. **Calculate:**
$$ t = \frac{\ln(1.1449)}{\ln(1.07)} $$
Calculate each logarithm:
- $\ln(1.1449) \approx 0.1352$
- $\ln(1.07) \approx 0.0677$
Then,
$$ t = \frac{0.1352}{0.0677} \approx 2.0 $$
8. **Interpretation:** The time period is approximately 2 years.
**Final answer:** (a) 2 years