Midterm review: weeks 1-8
SDLC, feasibility calculations, function points, critical path, requirements, use cases and class diagrams on a single page. Mixed midterm questions at the end.
The midterm covers weeks 1-8. The distribution of questions is usually like this: a few definition and multiple-choice questions (SDLC, methodology, types of feasibility, types of requirements), one or two calculations (NPV/ROI/payback, function points, critical path), one drawing (a use case diagram or class diagram) and one writing task (a use case description). This page collects the essence of each topic in a table, then tests you with mixed questions. First read the tables, then solve the questions without looking at the answers.
Topic map
| Week | Topic | How it appears on the exam |
|---|---|---|
| 1 | SDLC, analyst roles, methodologies | Definitions, the “which methodology” scenario |
| 2 | System request, feasibility | NPV, ROI, payback calculation; type of feasibility |
| 3 | Project management, function points, scope | FP calculation, definition of timeboxing/scope creep |
| 4 | Problem analysis, Gantt, PERT/CPM | Critical path and slack calculation, PIECES |
| 5 | Requirements and techniques | Requirement classification, choice of technique |
| 6 | Use case diagram | Extract actors and use cases from a scenario, draw |
| 7 | Use case description | Write a fully dressed one |
| 8 | CRC, class and object diagram | Draw a class diagram from a scenario, multiplicity |
Checklist for calculation questions
Feasibility (week 2)
- Build a table with the years as columns: benefit, cost, net, PV, cumulative.
- Year 0 is not discounted.
- NPV is written with the currency, ROI as a percentage, payback in years.
- In payback, divide by the crossover year’s own flow.
Function points (week 3)
TUFP = Σ (count x weight)
APC = 0.65 + 0.01 x PC (PC: 0..70)
AFP = TUFP x APC
LOC = AFP x lines/FP
effort = 1.4 x KLOC (person-months)
schedule = 3.0 x effort^(1/3) (months)| Low | Avg | High | |
|---|---|---|---|
| EI | 3 | 4 | 6 |
| EO | 4 | 5 | 7 |
| EQ | 3 | 4 | 6 |
| ILF | 7 | 10 | 15 |
| EIF | 5 | 7 | 10 |
CPM (week 4)
Forward : ES = max(predecessor EF), EF = ES + d
Backward: LF = min(successor LS), LS = LF - d
Slack = LS - ES
Critical path: slack = 0, the longest path
Check: the length of the critical path = project durationComparison tables for concept questions
Methodologies
| Situation | Suitable |
|---|---|
| Requirements clear and fixed, documentation mandatory | Waterfall, V-model |
| Requirements unclear, the user understands when they see it | System prototyping, agile |
| High technical risk, unclear requirements | Throwaway prototyping |
| Short schedule, priority parts first | Iterative, timeboxing, Scrum |
| Large, OO, with UML | Unified Process |
Requirements gathering
| Need | Technique |
|---|---|
| Deep, detailed information | Interview |
| Many people, cheap, broad | Questionnaire |
| Real behavior | Observation |
| Formal rules, forms | Document analysis |
| Joint decision, resolving conflict | JAD |
Use case relationships
| Relationship | When | Arrow |
|---|---|---|
| Include | Shared part that runs every time | Base → included |
| Extend | Conditional additional behavior | Extending → base |
| Generalization | Special kind | Child → parent, hollow triangle |
Class diagram relationships
| Relationship | Sentence | Symbol |
|---|---|---|
| Association | ”… is related to” | Solid line |
| Aggregation | “has a”, the part is independent | Hollow diamond at the whole |
| Composition | “is part of”, the part dies with the whole | Filled diamond at the whole |
| Generalization | “is a kind of” | Hollow triangle at the superclass |
Strategy for drawing questions
- List first, then draw. Write the actor/use case or class/attribute table on the side. When you move to the drawing you won’t forget anything.
- Mark every sentence in the scenario. Every sentence should correspond to at least one element. If a sentence is left unused, you missed something.
- Don’t leave multiplicity for last. The moment you draw each relationship, ask two questions: “How many B does one A have?” and “How many A does one B have?”
- Draw legibly. Lines should not cross; reposition the classes if necessary.
Use case description strategy
Write the template from memory: name, ID, importance, primary actor, stakeholders and interests, brief description, trigger (type), relationships, preconditions, normal flow, subflows, alternate/exceptional flows, postconditions. The normal flow should have 5-8 steps, each step starting with “The student …” or “The system …”. Write at least two alternate flows and state the return point.
Common mistakes (whole semester)
| Wrong | Right |
|---|---|
| The system proposal is the output of design | It is the output of analysis |
| Discounting year 0 | The factor for year 0 is 1 |
| APC = 0.65 × PC | APC = 0.65 + 0.01 × PC |
| Max in the backward pass | Min in the backward pass |
| A performance requirement is functional | Nonfunctional |
| The extend arrow from the base | From the extending one to the base |
| Multiplicity at its own end | Read from the opposite end |
| The diamond on the part side | On the whole side |
Test yourself
Exam-style questions. Solve them on paper first, then reveal the answer.
Which SDLC phase produces the system specification?
- Planning
- Analysis
- Design
- Implementation
Show answer
Planning → system request + feasibility + plan. Analysis → system proposal. Design → system specification. Implementation → the installed, working system.
A project costs 60,000 TL and yields 25,000 TL net per year for 3 years. At 12%, what is the NPV?
Show answer
PVs: , , . Total 60,045.78. NPV = 60,045.78 − 60,000 = 45.78 TL. Positive but marginal: if the discount rate rose a little, the project would turn negative. Although the nominal total is 75,000, the real gain is almost zero.
Same project: what is the simple payback period and the nominal ROI?
Show answer
Cumulative: −35,000, −10,000, +15,000. Payback = 2 + 10,000/25,000 = 2.4 years. ROI = (75,000 − 60,000) / 60,000 = 0.25 = 25%.
Counts: EI 4 low and 3 high; EO 2 average; EQ 3 low; ILF 2 low; EIF 1 high. PC = 40. Find TUFP and adjusted FP.
Show answer
EI: 4×3 + 3×6 = 30. EO: 2×5 = 10. EQ: 3×3 = 9. ILF: 2×7 = 14. EIF: 1×10 = 10. TUFP = 73. APC = 0.65 + 0.40 = 1.05. AFP = 73 × 1.05 = 76.65.
Tasks (days, predecessors): A 3 (none), B 2 (A), C 4 (A), D 3 (B, C), E 1 (D). Give the critical path, the duration and the slack of B.
Show answer
Forward pass: A 0-3, B 3-5, C 3-7, D max(5,7)=7 → 10, E 10-11. Duration 11.
Backward pass: E LS 10, D LF 10 LS 7, B LF 7 LS 5, C LF 7 LS 3, A LF min(5,3)=3 LS 0.
Slack B = 5 − 3 = 2. The critical path is the tasks with slack 0: A-C-D-E.
PERT estimate for o = 1, m = 3, p = 11 days?
Show answer
days.
Classify: 'Members' payment card data must never be stored on the gym's servers.'
- Functional
- Operational
- Performance
- Security
Show answer
A constraint about where data is stored and who can access it: security. It does not define a function but the security condition of a function.
Which technique is most likely affected by the Hawthorne effect?
- Questionnaire
- Document analysis
- Observation
- JAD
Show answer
A person who knows they are being watched changes their behavior. This directly affects observation.
'Checkout' always calls 'Calculate Total'; 'Apply Coupon' happens only if the customer enters a coupon code. Name both relationships to 'Checkout'.
Show answer
A shared part that runs every time is include, and the arrow leaves the base (Checkout). A conditional additional behavior is extend, and the arrow goes from the extending one (Apply Coupon) to the base.
A House has Rooms; if the house is demolished, its rooms no longer exist. A Room belongs to exactly one House, a House has at least one Room. Give the relationship and multiplicities.
Show answer
The part disappears with the whole and belongs to a single whole: composition. How many Houses does a Room have? 1 → at the House end. How many Rooms does a House have? 1..* → at the Room end.
In a use case description, where do you write 'If the card is declined, the system asks for another card and returns to step 5'?
- Normal flow
- Preconditions
- Alternate/exceptional flows
- Brief description
Show answer
The normal flow is the single success path. The declined case is a deviation, and it is written in the alternate/exceptional flow with the step number of the deviation (e.g. 6a), and the return point is stated too.
A university project has clear, stable, legally fixed requirements and auditors require full documentation. Which methodology is the safest choice?
- Scrum
- System prototyping
- Waterfall (or V-model)
- Throwaway prototyping
Show answer
If the requirements are clear and fixed and documentation is mandatory, structured methods (waterfall, V-model) fit. Agile and prototyping are strong when requirements are unclear.
Verification: The numeric answers (NPV, PVs, payback, ROI, TUFP/AFP, critical path, slack, PERT) were computed with node (verify/SEN2022/09.mjs, shared functions in lib.mjs). Conceptual questions were compared with the standard definitions on the week 1-8 pages.