wheel tractor scraper costing $$650,000$ delivered to the contractor will be used for $1500$ hours

for six years. At the end of the sixth year, its salvage value is estimated at $$200,000.$ It is rated at

$815$ hp and has a diesel engine with an operating factor of $0\mathrm{.}75.$ Tires for the scraper cost

$ $50,000$ and last for $3000$ hours. The crankcase capacity is $13$ gallons, and the lube oil must be

changed every $500$ hours. Assume the cost for the lube oil is $$10\mathrm{.}00/$gal and the cost of diesel fuel

is $$5\mathrm{.}00/$gal$.$ Interest, insurance tax, and storage total $22\%$ of the average annual investment.

Machine repairs will account for $80\%$ of the depreciation of the machine, and tire repair will

account for $10\%$ of the depreciation of the tires.

a$.$ Find the hourly owning and operating cost of the machine

b$.$ Suppose another dealer offers the same scraper for $$800,000$ but with a maintenance and

tire package that covers all machine repair and tire replacement$/$repair$.$ The machine

owner is responsible for buying and changing the lube oil. Which machine would be

more cost$-$effective per hour?