18 Find the compound interest earned when $\$ 50000$ is invested for 10 years at $6.5 \%$ p.a., with interest compounded half-yearly.

Step 1 ：Calculate the compound interest using the formula: Compound Interest = P * (1 + r/n)^(nt) - P, where P = 50000, r = 0.065, n = 2, and t = 10.

Step 2 ：Plug in the values and simplify: Compound Interest = 50000 * (1 + 0.065/2)^(2*10) - 50000

Step 3 ：Calculate the final result: \( \boxed{44791.90} \)