Light bulbs burn out according to the following table:
l = 1,000,000 l = 800,000 l = 600,000 l = 300,000 l = 0
0 1 2 3 4
A new plant has 2500 light bulbs. Burned out light bulbs are replaced with
new light bulbs at the end of each year. What is the expected number of new
light bulbs that will be needed at the end of year 3?
The answer is 970.