Tower cranes along a city skyline often indicate the success of economic development efforts. In early January 2013, more than 50 tower crane permits were in use in Washington, D.C. Independent random...

Tower cranes along a city skyline often indicate the success of economic development efforts. In early January 2013, more than 50 tower crane permits were in use in Washington, D.C. Independent random samples of items lifted by cranes at two different sites were obtained, and the weight (in tons) of each item was recorded for each. The summary statistics are given in the following table.