Monster, Inc. purchased a crane at a cost of $80,000. The crane has an estimated residual value of $5,000 and an estimated life of 8 years, or 12.500 hours of operation. The crane was purchased on January 1, 2017 and was used 2.700 hours in 2017 and 2,600 hours in 2018. If Monster uses the units-of-production method, what is the depreciation rate per hour for the crane? $6.00 $6.80 $2.36 $6.40