The average of allsubgroups becomes the centerline for the lower plotting area. Average of Ranges Example Step 7 - Calculate the upper control limit (UCL) and lower control limit (LCL)for the averages of the subgroups. At this point, your chart will look like aRun Chart. Now, however, the uniqueness of the Control Chart becomes evidentas you calculate the control limits.
Ford Motor Company recommends that the Crown Vic limit its towing to a trailer with a gross vehicle weight of 1500 lbs or less with a tongue weight not to exceed 150 lbs. See HERE.
A single vehicle with a GVWR of 10,000 lbs. or less including a tow dolly, if used. If the towing vehicle weighs 4,000 lbs. or more unladen, you may tow a: Trailer coach not exceeding 9,000 lbs. gross. Trailer coach or 5th-wheel travel trailer under 10,000 lbs. GVWR when towing is not for compensation. 5th-wheel travel trailer exceeding 10,000 lbs. but not exceeding 15,000 lbs.