Abdullah won the lottery on Monday and can take either $50,000 per year for 20 years, or $500,000 today. Khalid won the same lottery on Tuesday and has the same options for receiving the cash. A well respected financial advisor is hired by both Abdullah and Khalid. The advisor recommends that Abdullah take the $50,000 per year for 20 years but advises Khalid to take the $500,000 up front payment. How is it possible to give different advice to two clients regarding the exact same cash flows?