Suppose you want to save money to pay for a down payment on an apartment in 5 years’ time. One year from now, you will invest your $30,000 yearend bonus for the down payment. If you can invest at 15% per year, how much interest will you receive on your cash in 5 years? If you need $210,000 for the down payment, and you would like to top-up the remaining amount by investing a lump sum today, what is the amount you should invest?