Nationwide income from monthly sales data (rounded to the nearest $100,000) of Stay Flat vacuum hold-down tables for last year is shown below. Determine the expected value of the monthly income, if economic conditions remain the same.

Income $ per Month          Number of Months

500,000 ..........................                    4

600,000 ..........................                    2

700,000 ..........................                    1

800,000 ..........................                    2

900,000 ..........................                    3