Do it ASAp

Barbara and Fred have decided to put in an automatic sprinkler system at their cabin. They have requested bids, and the lowest price received is $5,500 from Water Systems Inc (WSI). They decide to do the job themselves and obtain a set of materials (plastic pipe, nozzles, fittings, and regulators) from an all-sales-are-final discount house for $1,100. They begin the installation and rent a trencher at $80 per day. Unfortunately, they quickly hit sandstone in many places of the yard and require a jackhammer and air compressor at another $80 per day. They keep all the rental equipment for 5 days. By this time, Fred has hurt his knee, and Barbara is sick of the project. They again contact WSI, who tells them that they can use only some of the materials, reducing the cost by $500, and only some of the trenching, reducing the cost by another $500, bringing the total to $4,500, finished and ready to go.

a. Of the ten principles, which one(s) is(are) well illustrated by this problem?

b. Of the systematic economic analysis techniques 7 steps, which one(s) is(are) well illustrated by this problem?