In 1937, Dr. Willis Haviland Carrier (1876-1950) developed an air conditioning system to cool the air in the Magma Copper Mine in Superior, Arizona.
It reduced the air temperature at the 3600 ft level from 133°F to 71.0°F after 4 months of operation. Each air conditioning unit in the system had a capacity of 140. tons of cooling and was driven by a 200. hp electric motor.
Determine the coefficient of performance of these units.