--- title: "COCOMO for 49,200 lines of code" subject: "Software Engineering" chapter: 8 key: "semester_5/software_engineering:cocomo-49200" source: https://www.bctengineer.com/q/semester_5/software_engineering/cocomo-49200 site: BCT Engineering --- # COCOMO for 49,200 lines of code Software Engineering · Chapter 8: Software Testing and cost Estimation - Asked in: year not given, 3+5 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_5/software_engineering/cocomo-49200 - Whole chapter: https://www.bctengineer.com/md/semester_5/software_engineering/chapter-8 ## Question What is COCOMO? Calculate COCOMO effort, development time in month, average staffing and productivity that is estimated to be 49,200 lines of code. ## Short answer COCOMO (Constructive Cost Model) estimates effort and schedule from KLOC. For 49,200 LOC (49.2 KLOC) in organic mode: Effort = 2.4 × 49.2^1.05 ≈ 143.5 person-months; Development time = 2.5 × 143.5^0.38 ≈ 16.5 months; Average staffing = 143.5/16.5 ≈ 9 persons; Productivity = 49200/143.5 ≈ 343 LOC/person-month. ## Answer #### What is COCOMO **COCOMO (Constructive Cost Model)** is an algorithmic cost estimation model developed by Barry Boehm (1981). It estimates the **effort** (person-months) and **development time** (months) of a software project from its size in thousands of delivered lines of code (KLOC). **Three modes (project classes):** | Mode | Description | a | b | c | d | |---|---|---|---|---|---| | Organic | Small team, familiar problem, flexible requirements (about 2–50 KLOC) | 2.4 | 1.05 | 2.5 | 0.38 | | Semi-detached | Medium size, mixed experience (about 50–300 KLOC) | 3.0 | 1.12 | 2.5 | 0.35 | | Embedded | Tight hardware/software/operational constraints | 3.6 | 1.20 | 2.5 | 0.32 | **Three levels:** *basic* (effort from size only), *intermediate* (size plus 15 cost drivers giving an effort adjustment factor) and *detailed* (cost drivers applied to each phase). **COCOMO II** (1995/2000) updated the model for modern development. Basic COCOMO equations: - Effort E = a × (KLOC)^b person-months - Development time D = c × (E)^d months - Average staffing = E / D persons - Productivity = KLOC / E #### Calculation for 49,200 lines of code Size = 49,200 LOC = **49.2 KLOC**. **Mode chosen: organic.** 49.2 KLOC lies within the usual organic range (up to about 50 KLOC), and no tight constraints, new technology or inexperienced team are mentioned. So a = 2.4, b = 1.05, c = 2.5, d = 0.38. **1. Effort** E = 2.4 × (49.2)^1.05 (49.2)^1.05 = 59.78 E = 2.4 × 59.78 = **143.5 person-months** **2. Development time** D = 2.5 × (143.47)^0.38 (143.47)^0.38 = 6.600 D = 2.5 × 6.600 = **16.5 months** **3. Average staffing** S = E / D = 143.47 / 16.50 = 8.69 ≈ **9 persons** **4. Productivity** P = Size / E = 49,200 / 143.47 = **342.9 LOC per person-month** (≈ 0.343 KLOC/PM) | Quantity | Result | |---|---| | Effort | 143.5 PM | | Development time | 16.5 months | | Average staffing | ≈ 9 persons | | Productivity | ≈ 343 LOC/PM | Note: if the project were treated as semi-detached (since 49.2 KLOC is close to 50 KLOC), the result would be E = 3.0 × 49.2^1.12 = 235.6 PM, D = 16.9 months, about 14 persons and 209 LOC/PM. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why was the organic mode chosen for 49.2 KLOC? A. It is within the usual organic range (up to about 50 KLOC) and no tight constraints are mentioned B. Embedded mode needs fewer than 10 KLOC C. All projects must use organic mode D. Organic has the largest exponent b Answer: A. The size is under about 50 KLOC and the problem states no tight constraints, new technology or inexperienced team. (Key point: Choice of COCOMO mode) 2. Which equation gives effort in basic organic COCOMO? A. E = 2.5 x (KLOC)^0.38 B. E = 2.4 x (KLOC)^1.05 person-months C. E = KLOC / D D. E = 3.0 x (KLOC)^1.12 Answer: B. Organic uses a = 2.4 and b = 1.05, giving E = 2.4 x 49.2^1.05, about 143.5 person-months. (Key point: Effort formula) 3. How are average staffing and productivity calculated? A. Staff = D / E; productivity = E / KLOC B. Staff = E x D; productivity = D / E C. Staff = E / D; productivity = size / E D. Staff = size / D; productivity = E / D Answer: C. Staff = E / D (143.47 / 16.5, about 9 persons) and productivity = size / E (about 343 LOC per person-month). (Key point: Staffing and productivity) 4. If the project were treated as semi-detached instead of organic, what would change? A. Nothing, results are identical B. Effort would be lower C. Only productivity would change D. Effort would be higher (about 235.6 PM) because a = 3.0 and b = 1.12 Answer: D. Semi-detached uses larger constants, giving more effort, a slightly longer time and more staff. 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