The total accumulated costs C(t) and revenues R(t) (in thousands of dollars), respectively, for a photocopying machine satisfy 1 _ 5 010:5? and R'(t)=5t5e ' where t is the time in years. Find the useful life of the machine, to the nearest year. What is the total profit accumulated during the useful life of the machine? The useful life of the machine is year(s). (Round to the nearest year as needed.) Using the useful life of the machine rounded to the nearest year, the total prot accumulated during the useful life of the machine is $ (Round to the nearest dollar as needed.) Calculate the indicated Riemann sum S for the function f(x) = 25 - 2x . Partition [0, 12] into four subintervals of equal length, and for each subinterval [Xk - 1,Xk ], let Ck = (Xk - 1 + 2Xk ) /3. SA = (Simplify your answer.)The ma_rginal average cost of producing x digital sports watches is given by the function 60:), where C(x) is the average cost in dollars. _ 1 ,700 _ C'(x)= 2 , C(100) = 21 X Find the average cost function and the cost function. What are the fixed costs? The average cost function is C(x) = D. The cost function is C(x) = The xed costs are $