In section b, when the faulty widgets are the ones that were supposed to be inspected 10th, 11th and 12th the inspector can finish inspection after inspecting only first 9 widgets. So it is not necessary for the inspector to inspect all faulty widgets to conclude inspection before inspecting 10 widgets (which is not the case for 9)
In section b, when the faulty widgets are the ones that were supposed to be inspected 10th, 11th and 12th the inspector can finish inspection after inspecting only first 9 widgets. So it is not necessary for the inspector to inspect all faulty widgets to conclude inspection before inspecting 10 widgets (which is not the case for 9)