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.
The 2011 Buick Enclave is rated for a maximum tow of 4,500 pounds. Back the Enclave up to the trailer's tongue. Ask someone to stand by and direct you. When the Enclave is in position, lower the trailer coupler onto the Enclave's hitch and lower the latch.