2. A farmer mixes two brands P and Q of cattle feed. Brand P, costing Rs 250 per bag, contains 3 units of nutritional element A, 2.5 units of element B and 2 units of element C. Brand Q costing Rs 200 per bag contains 1.5 units of nutritional element A, 11.25 units of element B, and 3 units of element C. The minimum requirements of nutrients A, B and C are 18 units, 45 units and 24 units respectively. Determine the number of bags of each brand which should be mixed in order to produce a mixture having a minimum cost per bag? What is the minimum cost of the mixture per bag?
Let farmer mix x bags of brand P and y bags of brand Q. Thus, .
The given information can be represented in the table as :
Vitamin A | Vitamin B | Cost | |
Food P | 3 | 5 | 60 |
Food Q | 4 | 2 | 80 |
requirement | 8 | 11 |
The given problem can be formulated as follows:
Therefore, we have
Subject to constraint,
The feasible region determined by constraints is as follows:
The corner points of the feasible region are
The value of Z at corner points is as shown :
corner points | ||
4500 | ||
2650 | ||
1950 | minimum | |
2400 |
Feasible region is unbounded, therefore 1950 may or may not be a minimum value of Z. For this, we draw and check whether resulting half plane has a point in common with the feasible region or not.
We can see a feasible region has no common point with .
Hence, Z has a minimum value 1950 at point .