A coal mine cost $1,004,000 and is estimated to hold 56,000 tons of coal. There is no residual value. During the first year of operations, 7,000 tons are extracted and sold. Calculate depletion expense for the first year.

Alarge tank is filled to capacity with 500 gallons of pure water. brine containing 2 pounds of salt per gallon is pumped into the tank at a rate of 5 gal/min. the well-mixed solution is pumped out at the same rate. find the number a(t) of pounds of salt in the tank at time t.

Suppose farmer lane grows and sells cotton in a perfectly competitive industry. the market price of cotton is $1.64 per kilogram, and his marginal cost of production is $1.44 per kilogram, which increases with output. assume farmer lane is currently earning a profit. can farmer lane do anything to increase his profit in the short run? farmer lane: a. cannot do anything to increase his profit. b. may or may not be able to increase his profit. c. can increase his profit by raising his price. d. can increase his profit by producing more output. e. can increase his profit by shutting down.

You are the manager of a large crude-oil refinery. as part of the refining process, a certain heat exchanger (operated at high temperatures and with abrasive material flowing through it) must be replaced every year. the replacement and downtime cost in the first year is $165 comma 000. this cost is expected to increase due to inflation at a rate of 7% per year for six years (i. e. until the eoy 7), at which time this particular heat exchanger will no longer be needed. if the company's cost of capital is 15% per year, how much could you afford to spend for a higher quality heat exchanger so that these annual replacement and downtime costs could be eliminated?