For a construction project, the minimum target concrete strength is 5000psi. A contractor is selecting between two of her mixing plants to provide the concrete mix for the project. The first plant has a standard deviation of 50psi. The second one has a standard deviation of 500psi It costs $70 to produce one ton of mix at average strength of 5000psi.: It costs and addition $20/extra 100 psi above the 5000 average. FOR PLANTA It costs and addition $5/extra 100 psi above the 5000 average. FOR PLANT B Which plant is more economical to use for this project, provided that the target average strength is met 99.5% of the time. Average Strength Plant A - Average Strength Plant B- Cost Per Ton Plant A - Cost Per Ton Plant B