Systems Engineering, Analysis, and Design practice questions

Answer: B) Rises the later it occurs in the life cycle

• AIncorrect. Later changes cost more.
• BCorrect. Early changes are cheapest.
• CIncorrect. It increases over time.
• DIncorrect. It's highest then.

Answer: D) Wear-out, where the failure rate rises

• AIncorrect. It depends on the failure pattern.
• BIncorrect. Replacement doesn't lower a constant rate.
• CIncorrect. Replacement restarts infant failures.
• DCorrect. Replacing before wear-out avoids failures.

Answer: A) 0.857

• ACorrect. Series reliability is 0.95³.
• BIncorrect. Multiply all three.
• CIncorrect. That's about 0.95²; use 0.95³.
• DIncorrect. That's a parallel arrangement.

Answer: A) Did we build the right system for the user's needs?

• ACorrect. Verification asks whether it meets its specifications.
• BIncorrect. That's verification.
• CIncorrect. That's cost control.
• DIncorrect. Validation concerns user needs.

Answer: B) 0.949

• AIncorrect. The product would be 0.81.
• BCorrect. \(\sqrt{0.9}\).
• CIncorrect. That halves it.
• DIncorrect. That's the product of two 0.9s.

Answer: B) Mean time to repair (MTTR)

• AIncorrect. That's reliability.
• BCorrect. Lower MTTR means easier maintenance.
• CIncorrect. That isn't maintainability.
• DIncorrect. That isn't maintainability.

Answer: A) Identifying stakeholders and drawing out their needs, constraints, and expectations

Requirements elicitation finds the stakeholders and draws out their needs and constraints, which then become formal requirements. Verification, functional allocation and configuration management are separate, later activities.

• ACorrect. Elicitation is the first step of requirements work. It finds the stakeholders and draws out their needs and constraints, which are later analyzed and written as formal requirements.
• BIncorrect. This is verification, which happens after design and build. It checks the product against requirements that already exist; it does not find out what stakeholders need.
• CIncorrect. This is functional allocation, a design activity. It comes after requirements have been gathered and analyzed.
• DIncorrect. This is configuration management. It controls changes to baselined items; it does not discover stakeholder needs.

Answer: C) Interface control document

An interface control document sets out the physical, electrical, and data connections between subsystems, so separately developed parts are compatible when integrated.

• AIncorrect. A WBS splits the project's work and deliverables into manageable elements for planning and cost control. It does not specify technical connections between units.
• BIncorrect. A ConOps describes, from the user's point of view, how the system will be operated and used. It does not specify pinouts or message formats.
• CCorrect. An ICD defines the physical, electrical, and data connections between systems or subsystems, so independently developed units fit together at integration.
• DIncorrect. An RTM links requirements to their sources, design elements, and verification activities. It does not define how two units physically or logically connect.

Answer: A) It results from interactions among components and is not found in any single part

An emergent property is a whole-system property that comes from interactions among components. It cannot be found in, or predicted from, any single component on its own.

• ACorrect. Emergent properties, such as safety or overall performance, exist only when the whole system is considered. They come from the way components interact.
• BIncorrect. That describes an additive (aggregate) property. Emergent properties cannot be predicted from the components alone, because they depend on interactions.
• CIncorrect. A property owned by one component is a component-level property. An emergent property exists only at the level of the whole system.
• DIncorrect. Emergent properties can be desirable or undesirable, and they are present whenever the system operates, not only when it fails. Systems engineering tries to anticipate them during design.

Answer: B) 120

• AIncorrect. Multiply, don't add.
• BCorrect. RPN = S × O × D.
• CIncorrect. Include detection.
• DIncorrect. Include occurrence.