You have to determine the cost for 4.5 inches of the construction using the graph.
The height is on the y-axis, and the cost is on the x-axis.
First, locate 4.5 in the y-axis, which is the value in the midpoint between 4 and 5.
Draw a horizontal line until you intersect with the line, then draw a vertical line from the function until the x-axis:
The line crosses the x-axis at the midpoint between values 102 and 127.5 to determine the value at this point you have to average both costs:
[tex]\frac{127.5+102}{2}=\frac{229.5}{2}=114.75[/tex]
The cost of 4.5 inches of construction is $114.5
