A construction site requires a minimum of 10,000 m3 of sand and gravel mixture. The mixture must contain no less than 5,000 m3 of sand and no more than 6,000 m3 of gravel. Materials may be obtained from two sites: 30% of sand and 70% gravel from site 1 at a delivery cost of $5.00 per m3 and 60% sand and 40% gravel from site 2 at a delivery cost of $7.00 per m3

a) Formulate the problem as a Linear Programming problem

b) Solve using Excel Solver