$${\left({\frac{{\mathtt{15\,000}}}{{\mathtt{10\,000}}}}\right)}^{{\mathtt{4}}}{\mathtt{\,-\,}}{\mathtt{1}}$$
+118608 $$\\15000=10000(1+r)^4\\\\
3=2(1+r)^4\\\\
1.5=(1+r)^4\\\\
1.5^{0.25}=1+r\\\\
r=1.5^{0.25}-1\\\\$$
$${{\mathtt{1.5}}}^{\left\{{\mathtt{0.25}}\right\}}{\mathtt{\,-\,}}{\mathtt{1}} = {\mathtt{0.106\: \!681\: \!919\: \!700\: \!321\: \!6}}$$
So the interest rate is approximately 10.67%
+118608 $$\\15000=10000(1+r)^4\\\\
3=2(1+r)^4\\\\
1.5=(1+r)^4\\\\
1.5^{0.25}=1+r\\\\
r=1.5^{0.25}-1\\\\$$
$${{\mathtt{1.5}}}^{\left\{{\mathtt{0.25}}\right\}}{\mathtt{\,-\,}}{\mathtt{1}} = {\mathtt{0.106\: \!681\: \!919\: \!700\: \!321\: \!6}}$$
So the interest rate is approximately 10.67%
