As my colleagues and I offer guidance on the American Library Association’s (ALA) more than $60 million in investments, some of the questions that arise are the same ones you may consider when managing a personal retirement account: - What investments should I choose (e.g., stocks, bonds, exchange-traded funds, mutual funds)? - Which financial services company fits my needs (e.g., Charles Schwab, Fidelity, TIAA, Vanguard)? - How much will I take out of my account each year as a distribution? That last decision is significant, because it affects how long the money will last and continue to grow, and it’s the one I will discuss in this column. ### Compounding and the Rule of 72 The Rule of 72 is a central principle for estimating how quickly an investment will grow. It says that compound interest will double an investment in 72 years divided by the interest rate (if you express it as an integer rather than a percentage). To illustrate: Say you have $100 in a savings account that gets 4% interest.…