Exercise
May 14'23
Answer
Key: D
The development factors are:
[[math]]
0-1: \frac{1}{3} \left( \frac{7,900}{2,500} + \frac{8,700}{2,800} + \frac{7,500}{2,500}\right) = 3.089 \quad 1-2: \frac{1}{3} \left( \frac{12,900}{8,700} + \frac{10,700}{7,500} + \frac{8,800}{6,400}\right) = 1.428
[[/math]]
[[math]]
2-3: \frac{1}{3} \left (\frac{12,600}{10,700} + \frac{10,200}{8,800} + \frac{8,800}{7,300} \right) = 1.181 \quad 3-4: \frac{1}{2} \left( \frac{11,500}{10,200} + \frac{9,800}{8,800} \right) = 1.1205 \quad 4-5: 1
[[/math]]
The cumulative factors are 0-5: 5.8372, 1-5: 1.8897, 2-5: 1.3233, 3-5: 1.1205; 4-5: 1.
The B-F reserve is [25,000(1 – 1/1.1205) + 26,000(1 – 1/1.3233) + 27,000(1 – 1/1.8897) + 28,000(1 – 1/5.8372)](0.55) = 24,726.