Homework # 4

3-9. Prepare a composite (weighted) index for housing construction cost in 2008, using the following data.

In = [((W1*(Cn1/Ck1) + W2*(Cn2/Ck2) + Wm*(Cnm/Ckm))/W1 + W2 + …Wm] *Ik

In = [((.7 *(62/41) + 0.05*(57/38) + .25*(53/33)/(.7 + 0.05 + .25)] * 100

In = [(1.058 + 0.075+ 0.4015)/1]*100 = 1.5345*100 = 153.45

3-16. Four hundred pounds of copper go into a 2,000-square-foot, newly constructed house. Today’s price of copper is $3.50 per pound. If the cost of copper is expected to increase 4.5% per year into the foreseeable future, what is the cost of copper going to be in a new 2,400 square foot house 10 years from now. Assume the cost capacity for increases of copper in houses equals 1.0.

In ten years you will need (2400sq-ft/2000sq-ft) * 400lb-copper = 480lb-copper

For one year increase $3.50 * 0.045 = $0.1575 + $3.50 = $3.6575

“      two   “          “        $3.6575 * 0.045 = $0.1658 + 3.6575 $3.822

“     three “         “        $3.822 * 0.045 = $0.17199 + $3.822 = $3.9939

“      four  “          “        $3.9939 * 0.045 = $0.1797 + $3.9939 = $4.1736

“      five   “          “        $4.1736 * 0.045 = $0.1878 + $4.1736 = $4.3614

“      six     “          “        $4.3614 * 0.045 =$0.19626 + $4.3614 = $4.55766

“    seven “          “        $4.5576 * 0.045 = $0.20509 + $4.5576 = $4.76269

“    eight  “          “        $4.76269 * 0.045 = $0.2143 + $4.76269 = $4.9770

“     nine  “          “        $4.9770  * 0.045 = $0.22396 + $4.9770 = $5.2009

“     ten    “          “        $5.2009 * 0.045 = $0.2340 + 5.2009 = $5.4349f

So if the capacity factor = 1 you need 480lb-copper * $5.4349per-lb = $2608.7728

or

3-17. The structural engineering design section within the engineering department of a regional electrical utility corporation has developed several standard designs for a group of similar transmission towers. The design for each tower is based on standard designs. A transmission line project involving 50 towers has been approved. The estimated number of engineering hours needed to accomplish the first detailed tower design is 126. Assuming a 95% learning curve.

1. What is the estimate of the number of engineering hours needed to design the eight and last tower in the project?
2. What is the estimate of the cumulative average hours required for the first five designs?