1. **Stating the problem:**
Haleema invests 3700 into a bank account that compounds interest monthly at a rate that makes it equal to another account compounding yearly at 5% after one year. We need to find the amount in her account after 2 years and 11 months.
2. **Formula for compound interest:**
The compound interest formula is $$A = P\left(1 + \frac{r}{n}\right)^{nt}$$ where:
- $A$ is the amount after time $t$,
- $P$ is the principal (initial amount),
- $r$ is the annual interest rate (decimal),
- $n$ is the number of compounding periods per year,
- $t$ is the time in years.
3. **Find the monthly interest rate:**
Given yearly rate $r = 0.05$ and monthly compounding $n=12$, the monthly rate $i$ satisfies:
$$\left(1 + i\right)^{12} = 1 + 0.05$$
4. **Calculate monthly interest rate $i$:**
$$1 + i = (1.05)^{\frac{1}{12}}$$
$$i = (1.05)^{\frac{1}{12}} - 1$$
5. **Calculate $i$ numerically:**
$$i \approx 1.05^{0.0833333} - 1 \approx 1.004074 - 1 = 0.004074$$
6. **Calculate total time in months:**
2 years 11 months = $2 \times 12 + 11 = 35$ months.
7. **Calculate amount after 35 months:**
$$A = 3700 \times (1 + 0.004074)^{35}$$
8. **Calculate the power:**
$$ (1.004074)^{35} \approx e^{35 \times \ln(1.004074)} \approx e^{35 \times 0.004066} = e^{0.1423} \approx 1.153$$
9. **Calculate final amount:**
$$A \approx 3700 \times 1.153 = 4266.1$$
10. **Round to nearest penny:**
£4266.10
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**Next problem:**
Center $g$ is increased by 26% and $h$ is decreased by 11%. Find the percentage change in $$\frac{g^2}{2h}$$.
11. **Original expression:**
$$\frac{g^2}{2h}$$
12. **New values:**
$$g_{new} = g \times 1.26$$
$$h_{new} = h \times 0.89$$
13. **New expression:**
$$\frac{(1.26g)^2}{2 \times 0.89h} = \frac{1.26^2 g^2}{2 \times 0.89 h} = \frac{1.5876 g^2}{1.78 h}$$
14. **Simplify ratio of new to old:**
$$\frac{\frac{1.5876 g^2}{1.78 h}}{\frac{g^2}{2h}} = \frac{1.5876}{1.78} \times 2 = \frac{1.5876 \times 2}{1.78} = \frac{3.1752}{1.78} \approx 1.783$$
15. **Percentage change:**
$$ (1.783 - 1) \times 100\% = 78.3\%$$ increase.
**Final answers:**
- Amount in account after 2 years 11 months: £4266.10
- $\frac{g^2}{2h}$ has increased by 78% (to nearest 1%)
Compound Interest Increase 21908A
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