Lumber Costs Lumber that is used to frame walls of houses is frequently so...

Lumber Costs Lumber that is used to frame walls of houses is frequently sold in lengths that are multiples of 2 feet. If the length of a board is not exactly a multiple of 2 feet, there is often no charge for the additional length. For example, if a board measures at least 8 feet, but less

than 10 feet, then the consumer is charged for only 8 feet.

(a) Suppose that the cost of lumber is $0.80 every 2 feet. Find a formula for a function ƒ that computes the cost of a board x feet long for

(b) Use a graphing calculator to graph ƒ.

(c) Determine the costs of boards with lengths of 8.5 feet and 15.2 feet.