Problem 12.6.1: You are a Construction Engineer working for an asphalt paving contractor. The : general superintendent is concerned about the allowances for small tools and supplies that are included in bids for jobs. Obviously, a bid allowance that is too low leads to loss of profits, whereas an allowance that is too high may lead to loss of jobs to competitors. The allowance for small tools and supplies currently used in bid development is 10 cents per ton of asphalt placed, and the superintendent wants to know if this factor is still valid, if any particular jobs have significantly overrun the allowance, and if there is any time trend in the small tools expense. Data on 19 actual jobs, showing the actual tons of asphalt placed and the actual expenditures on small tools and supplies, are shown in Table 12.5, in chronological order. 36 Table 12.5 Problem Data Description Job # Tons Asphalt Placed $ small tools Guilford Road Resurfacing 1035 8961 2080 Mebane Oaks Road and Highway 119 1036 17406 2726 1037 32048 3380 1038 12377 1954 1040 16921 5973 20452 56836 9217 20454 2632 704 20459 15885 2882 State Highway 49 at Trollingwood Road State Highway 49 at Orange Street Alamance at Guilford Road Davidson County Resurfacing City of Reidsville City of Winston US 52 Northbound Lanes Shoulder US 52 Southbound Lanes Shoulder US 220 at Guilford Road City of Thomasville WBS 37193 Business 40 and US 431 Ramps WBS 36788 20461 9524 2626 20462 10196 2467 20466 6189 379 20469 2905 1083 20472 4833 1899 20474 3599 1158 20475 10116 4641 Bluff School Road 20476 1684 442 Kivett Drive 20477 2561 1397 Orange and Caswell 20480 13725 2275 Davidson County 20484 20998 1560 Show a control chart for dollars expended on small tools per ton of asphalt, as a function of time. Is this process homogeneous (in statistical control)? Explain why or why not. Show upper and lower process limits. Is it possible to define specification limits? If so, what should they be? Do any jobs stand out, high or low? Is the actual expense for small tools a linear function of the job size, as is implied by the 10 cents per ton factor, or is some other relationship with job size better? Problem 12.6.1: You are a Construction Engineer working for an asphalt paving contractor. The : general superintendent is concerned about the allowances for small tools and supplies that are included in bids for jobs. Obviously, a bid allowance that is too low leads to loss of profits, whereas an allowance that is too high may lead to loss of jobs to competitors. The allowance for small tools and supplies currently used in bid development is 10 cents per ton of asphalt placed, and the superintendent wants to know if this factor is still valid, if any particular jobs have significantly overrun the allowance, and if there is any time trend in the small tools expense. Data on 19 actual jobs, showing the actual tons of asphalt placed and the actual expenditures on small tools and supplies, are shown in Table 12.5, in chronological order. 36 Table 12.5 Problem Data Description Job # Tons Asphalt Placed $ small tools Guilford Road Resurfacing 1035 8961 2080 Mebane Oaks Road and Highway 119 1036 17406 2726 1037 32048 3380 1038 12377 1954 1040 16921 5973 20452 56836 9217 20454 2632 704 20459 15885 2882 State Highway 49 at Trollingwood Road State Highway 49 at Orange Street Alamance at Guilford Road Davidson County Resurfacing City of Reidsville City of Winston US 52 Northbound Lanes Shoulder US 52 Southbound Lanes Shoulder US 220 at Guilford Road City of Thomasville WBS 37193 Business 40 and US 431 Ramps WBS 36788 20461 9524 2626 20462 10196 2467 20466 6189 379 20469 2905 1083 20472 4833 1899 20474 3599 1158 20475 10116 4641 Bluff School Road 20476 1684 442 Kivett Drive 20477 2561 1397 Orange and Caswell 20480 13725 2275 Davidson County 20484 20998 1560 Show a control chart for dollars expended on small tools per ton of asphalt, as a function of time. Is this process homogeneous (in statistical control)? Explain why or why not. Show upper and lower process limits. Is it possible to define specification limits? If so, what should they be? Do any jobs stand out, high or low? Is the actual expense for small tools a linear function of the job size, as is implied by the 10 cents per ton factor, or is some other relationship with job size better