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