Math rates Tutoring is planning to create a math study workbook that they will sell to schools in their area. Math rates Tutoring has determined that if they produce 1000 of these workbooks, it will cost them $6,000. It will cost $15,000 to produce 4000 workbooks.

a) Using this information, find a linear cost function for the workbooks. Show your work and write your answer using function notation.

b) Math rates Tutoring has hired a consultant to forecast their revenue. (because they will sell directly to schools under complicated contract pricing, revenue is not just quantity sold times price). The consultant has provided Math rates Tutoring with the Revenue forecast below: (you dont have the formula that generates this graph and you dont need it)