A process engineer is performing tests on a unit that has been giving problems. A crucial measurement is the average concentration of a particular component in the feed stream to the unit. The analytical method available for determining the concentration of this key component is very expensive and time consuming, such that the budget allows only four sam- ples to be drawn for the purpose of determining the average concentration. Further, the experiment will take place over a 2-h period. Suggest when the samples should be taken and how the best possible average concentration can be determined. Hint: One way to compute an average of a function, f(t), is to inte- grate over the time interval and divide by the interval width. That is, Average (f(t)) = 1 tmax Imax of(1) dt