A business produces products X and Y. In one week, 100 kgs of materials and 300 direct labour hours are available for production.

Product X

Direct labour per unit= 6 hours

Contribution per unit = 4

Materials per unit = 1kg

Product Y

Direct labour per unit = 3 hours

Contribution per unit = 5

Materials per unit = 2kg

When building a linear programming model, what is the objective function for maximising profits?

1. Minimise 1X + 2Y

2. Minimise 4X + 5Y

3. Minimise 6X + 3Y

4. Maximise 4X + 5Y

5. Maximise 6X + 3Y

6. Maximise 1X + 2Y