A local utility company operates coal-fired boilers to drive generators. The company can purchase different types of coals and blend them to meet the requirements for burning in the boiler. The following table shows the characteristics of the different types of coals:

Type	BTU/lb	Ash%	Moisture %	Cost($/lb)
A	11,500	13%	10%	$ 2.49
B	11,800	10%	8%	$ 3.04
C	12,200	12%	8%	$ 2.99
D	12,100	12%	8%	$ 2.61

The mixture must have the following characteristics:

BTU/lb at least 11900

Ash content at most 12.2%

Moisture content at most 9.4%

Develop a linear programming model to find the best coal blend which meets the requirements and minimizes the cost.

How much is the optimum mixture cost per pound ($/lb)? Enter the number without a $.

In the utility company problem, which type of coal has the highest proportion in the mix?

In the utility company problem, if ash content is not an issue what will be the minimum cost of the mixture?