Suppose you have $$1000$ side money. You have two options: spend this money today, or save it for the future. You are offered the following investment opportunity that if you lend the $$1000$ out today, you will receive $$1150$ dollars one year later. You think this is a good deal, accept it$,$ and lend your money out. To keep a track of the price level, you check the Bureau of Labor Statistics webpage, and find that the CPI for today is $500.$