You can purchase an optical scanner today for $550. The scanner provides benefits worth $90 a year. The expected life of the scanner is 10 years. Scanners are expected to decrease in price by 25% per year. Suppose the discount rate is 12%. When is the best time to purchase the scanner? (Round your answer to the nearest cent.) NPV is maximized when you wait date NPV will be equivalent to $ years to purchase the scanner. At this today