Several fast food restaurants advertise quarter-pound hamburgers. This could be interpreted as meaning half the hamburgers made have an uncooked weight of at least a quarter-pound and half have a weight that is less. An inspector checks 20 uncooked hamburgers at each restaurant.
(a) Make a p chart using the centerline and control limits calculated for p0 = .5.
(b) Suppose that five restaurants have 8, 11, 7, 15, and 10 underweight hamburgers in samples of size 20. Graph the corresponding proportions on your p chart.
(c) Identify any restaurants where the chart signals "out of control."