A company needs a machine for the next 4 years. The following table shows data for 3 alternative types of machines that can be used. BV symbolizes the purchase price (cost) of a new machine and SV (k) the resale price (revenue) of a machine that has already operated for k years. The decision to resell an existing and / or purchase a new machine is made on an annual basis (ie at times t = 0, 1, 2 and 3). The type A machine has a lifespan of 1 or 2 years, while the type B and C machines have a lifespan of 2 or 3 years (depending on the probabilities given). At the beginning of the first year (t = 0), no machine is available, so a new one will have to be purchased. The aim is to find a sequence of machine purchase / resale decisions, so that there is one machine available in each of the 4 years, and the total cost (costs - revenue) to be minimized. Solve this problem with dynamic programming.

	P (L = 1)	P (L = 2)	P (L = 3)	BV	SV(1)	SV(2)	SV(3)
Type	0,5	0,5	0	100	50	0	-
Type	0	0,6	0,4	200	-	100	50
Type C	0	0,3	0,7	300	-	200	100