o STATEMENT OF PROBLEM

A straight four-foot wide path going up a hill must be paved to a point and then continue with steps. The paving can only be done on portions of the path that have a slope of magnitude less than 1/3. The rest of the hill must be furnished with steps. Each step will rise exactly 8 inches high. Surveyors have gathered the following elevation data along the path.

Input := 

PathData = {{0,50},{20,47},{40,43},{60,38},{80,32},
	{100,25},{120,17},{140,8},{160,6},{180,2},{200,0}};
Input := 

TableForm[
	PathData,
	TableHeadings ->
		{None,{"Dist from top of hill [feet]",
						"hill height [feet]"}},
	TableAlignments -> Center]
Output =

   Dist from top of hill [feet]   hill height [feet]
                0                         50

                20                        47

                40                        43

                60                        38

                80                        32

               100                        25

               120                        17

               140                        8

               160                        6

               180                        2

               200                        0
Input := 

p1 = ListPlot[PathData,
	PlotStyle -> PointSize[.02]]
Output =

-Graphics-

All relationships are in feet. For example, the ordered pair (60,38) represents a horizontal distance of 60 feet from the top of the hill, and 38 vertical feet from the bottom.

+ 1) Fit the hill side data to a 3rd degree polynomial of the form
y = A x^3 + B x^2 + C x + D.
Does this offer a reasonable fit?
You'll use this path equation to answer the rest of the questions.

+ 2) How many steps are necessary, and what are their individual lengths, i.e. tread lengths? (You'll have to build a table since each step will likely have a unique tread length.)

+ 3) How long is the paved section of the path? (Be sure to give the true length -- not the horizontal length.)

+ 4) The cost of paving is $2.00 per square foot and the cost of putting in steps is $2.50 per square foot (horizontal area only). How much will the path cost to build?