Your parents will retire in exactly 18 years. They currently have S300,000 saved today, and they think they will need S1,500,000 at retirement.

Your parents will retire in exactly 18 years. They currently have S300,000 saved today, and they think they will need S1,500,000 at retirement. What annual interest rate must they earn to reach their goal, assuming they do not save additional funds? You MUST use timelines.