The plasma concentration for a patient taking an oral drug is given by: Cp(t)=20 (e-0.2t - e-2t)
where t is in hours and Cp is in mg/L. Calculate the AUC2hr-12hr using the following methods:
(i) Analytical integration.
(ii) Sum of areas of rectangles-A. Plot Cplt) first. Then divide the time period in 5 equally spaced time intervals and calculate the sum of the areas of each of the rectangles having as base a given time interval and as height the value of Cp at the beginning of that time interval.
(iii) Sum of areas of rectangles-B. Same as in previous question, but use the value of Cp at the end of any given time interval.
(iv) Sum of areas of trapezoids using the same time intervals.
Briefly comment the differences among the results obtained above.

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.