Pipe is to be laid from point A in a rectangular plot of size 10 x 20 feet to a point P on side BC and from there on to C as shown in red in the figure below. The cost of laying pipe within the plot is $c per foot (it must be underground), while the cost of laying pipe along the side of the plot is $d per foot. 10 20 (a) Determine the total cost, f(x), as a function of c, d and x, where x is the distance from P to B. (Note that f(x) is discontinuous at x = 0.) f(x) = dollars (b) What is the cost of laying the pipe on the side of the plot (x = 0) when c = 30 and d = 25? (Round your answer to the nearest cent.) $ (c) What is the least cost of laying the pipe when c = 30 and d = 25? (Round your answer to the nearest cent.)

Extreme Protection, Inc. manufactures helmets for skiing and snowboarding. The fixed costs for one model of helmet are $7900 per month. Materials and labor for each helmet of this model are $55, and the company sells this helmet to dealers for $85 each. (Let x represent the number of helmets sold. Let C, R, and P be measured in dollars.) (a) For this helmet, write the function for monthly total costs C(x). C(x) = (b) Write the function for total revenue R(x). R(x) = (c) Write the function for profit P(x). P(x) = (d) Find C(200). C(200) = Interpret C(200). O When this many helmets are produced the cost is $200. O This is the cost (in dollars) of producing 200 helmets. O For every additional helmet produced the cost increases by this much. O For each $1 increase in cost this many more helmets can be produced. Find R(200). R(200) =