A mining company estimates that the marginal cost of extracting x tons of copper ore from a mine is
0.4 + 0.008x,
measured in thousands of dollars per ton. Start-up costs are $130,000. What is the cost of extracting the first 50 tons of copper? What is the cost of extracting the next 50 tons.

Question

A mining company estimates that the marginal cost of extracting x tons of copper ore from a mine is 
0.4 + 0.008x,
 measured in thousands of dollars per ton. Start-up costs are $130,000. What is the cost of extracting the first 50 tons of copper? What is the cost of extracting the next 50 tons.

imsaucin01 · Answer

The equation 0.6 + 0.008x is in thousand of dollars per ton.
To put it in actual dollars, that would be 600 + 8x dollars, where x is in tons.
There is also an additional 100,000 worth of start up costs.
That would make the equation -100,000 + 600 + 8x.  Is this correct?  That's how I read it.

The first 50 is -99,400 + 400 = -99,000.
The next 50 is 400.