To determine how long it takes for $5,000 to grow to $7,500 at 8% interest, both compounded semiannually and continuously, the relevant formulas are A=P(1+r/m)^(mt) for compound interest and A=Pe^(rt) for continuous compounding. The discussion highlights the importance of showing calculations and results to receive accurate assistance. Without specific details on the calculations attempted or the textbook's answer, it's challenging for others to provide help. Clarifying these points would enable more effective guidance on achieving the correct answer. Accurate application of the formulas is essential for resolving the investment growth question.