COCOMO model in Software Engineering - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the basic COCOMO effort estimation formula.

Software Engineering

effort = a * (KLOC [1] b)

Drag options to blanks, or click blank then click option'

A-

B**

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication '*' instead of exponentiation '**'.

The COCOMO basic effort estimation formula uses exponentiation of KLOC by b, so '**' is the correct operator.

2fill in blank

medium

Complete the code to calculate development time (TDEV) in the COCOMO model.

Software Engineering

TDEV = c * (effort [1] d)

Drag options to blanks, or click blank then click option'

A+

B-

C*

D**

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication '*' instead of exponentiation '**'.

Development time is calculated by raising effort to the power of d, so '**' is correct.

3fill in blank

hard

Fix the error in the COCOMO effort calculation code.

Software Engineering

effort = a * (KLOC [1] b)

Drag options to blanks, or click blank then click option'

A**

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' which multiplies instead of exponentiating.

The error is using '*' instead of '**' for exponentiation. The correct operator is '**'.

4fill in blank

hard

Fill both blanks to complete the COCOMO effort and time formulas.

Software Engineering

effort = a * (KLOC [1] b)
TDEV = c * (effort [2] d)

Drag options to blanks, or click blank then click option'

A**

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication '*' instead of exponentiation '**'.

Both formulas require exponentiation '**' for the power operations.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension for COCOMO effort multipliers.

Software Engineering

effort_multipliers = {factor: rating[1]1.0 for factor, rating in ratings.items() if rating [2] [3]

Drag options to blanks, or click blank then click option'

A*

B>

C3

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '*' for multiplication.

Using '<' instead of '>' in the condition.

The comprehension multiplies ratings, filtering those greater than 3.

Practice

1. What is the primary purpose of the COCOMO model in software engineering?

easy

A. To manage software version control

B. To design the user interface of software

C. To test software for bugs

D. To estimate the effort and time required for a software project

Solution

1. Step 1: Understand COCOMO's role

   COCOMO stands for Constructive Cost Model and is used to estimate effort and time.

2. Step 2: Compare options

   Only To estimate the effort and time required for a software project describes estimation of effort and time, which matches COCOMO's purpose.

3. Final Answer:

   To estimate the effort and time required for a software project -> Option D

4. Quick Check:

   COCOMO estimates effort and time [OK]

Hint: COCOMO estimates project effort and duration [OK]

Common Mistakes:

• Confusing COCOMO with testing or design tools
• Thinking COCOMO manages code versions
• Assuming COCOMO is for UI design

2. Which of the following is a correct formula used in the basic COCOMO model to estimate effort (in person-months)?

easy

A. Effort = a * (KLOC)^b

B. Effort = a + b * KLOC

C. Effort = a / (KLOC)^b

D. Effort = a * b + KLOC

Solution

1. Step 1: Recall COCOMO effort formula

   Basic COCOMO uses Effort = a * (KLOC)^b, where a and b are constants and KLOC is thousands of lines of code.

2. Step 2: Check options

   Only Effort = a * (KLOC)^b matches the correct formula structure with multiplication and exponent.

3. Final Answer:

   Effort = a * (KLOC)^b -> Option A

4. Quick Check:

   Effort formula uses multiplication and power [OK]

Hint: Look for multiplication and exponent in effort formula [OK]

Common Mistakes:

• Using addition or division instead of multiplication and power
• Mixing constants incorrectly
• Confusing effort with time formulas

3. Given a software project with 50 KLOC, and basic COCOMO constants a=2.4 and b=1.05, what is the estimated effort in person-months? (Use formula: Effort = a * (KLOC)^b)

medium

A. About 100 person-months

B. About 150 person-months

C. About 130 person-months

D. About 90 person-months

Solution

1. Step 1: Apply the formula with given values

   Effort = 2.4 * (50)^1.05. Calculate 50^1.05 ≈ 60.8.

2. Step 2: Calculate effort

   Effort ≈ 2.4 * 60.8 = 145.9 person-months, approximately 150 person-months.

3. Final Answer:

   About 150 person-months -> Option B

4. Quick Check:

   2.4 * 50^1.05 ≈ 146 [OK]

Hint: Calculate power first, then multiply by constant a [OK]

Common Mistakes:

• Forgetting to raise KLOC to power b
• Using wrong constants
• Rounding too early causing big errors

4. A developer wrote this COCOMO effort estimation code snippet but it gives wrong results:

effort = a * KLOC ** b

Given a=2.5, b=1.1, KLOC=40, what is the likely error?

medium

A. Incorrect order of operations causing wrong calculation

B. Not converting KLOC to thousands of lines

C. No error; code is correct

D. Using exponentiation operator incorrectly in this context

Solution

1. Step 1: Analyze the formula and code

   The code uses Python exponentiation operator ** correctly for Effort = a * KLOC^b.

2. Step 2: Check variable values and units

   KLOC is already in thousands of lines (40), so no conversion needed. The formula and code match.

3. Final Answer:

   No error; code is correct -> Option C

4. Quick Check:

   Code matches formula and units [OK]

Hint: Check if code matches formula and units exactly [OK]

Common Mistakes:

• Assuming exponent operator is wrong in Python
• Forgetting KLOC unit is already thousands
• Thinking order of operations is incorrect

5. A software project is classified as 'organic' in COCOMO with constants a=2.4, b=1.05, c=2.5, d=0.38. If the project size is 30 KLOC, what is the estimated development time (in months)? Use formulas:
Effort = a * (KLOC)^b
Time = c * (Effort)^d

hard

A. About 13.5 months

B. About 10.2 months

C. About 7.3 months

D. About 8.5 months

Solution

1. Step 1: Calculate effort

   Effort = 2.4 * (30)^1.05. Calculate 30^1.05 ≈ 35.6. Effort ≈ 2.4 * 35.6 = 85.4 person-months.

2. Step 2: Calculate development time

   Time = 2.5 * (85.4)^0.38. Calculate 85.4^0.38 ≈ 5.42. Time ≈ 2.5 * 5.42 = 13.55 months.

3. Final Answer:

   About 13.5 months -> Option A

4. Quick Check:

   Time = c * Effort^d ≈ 13.5 months [OK]

Hint: Calculate effort first, then apply time formula [OK]

Common Mistakes:

• Calculating time without effort first
• Using wrong constants for organic projects
• Rounding intermediate values too early