Figure 2 shows the feasible region as the shaded region on the left-hand side of the figure.
We can also represent possible solutions to the minimization problem in the (θ_H,θ_L) plane by drawing contours of the objective function. These contours are lines of the form θ_H-θ_L=C , where C is a constant. Figure 2 shows a few lines for interval widths (i.e., values of C ) of 0, .2, and .3693. The confidence interval with the minimum width that meets all of the constraints will be represented by the first contour line that touches the feasible region.