Iterative Model Development, Review and Validation CT-MBT Practice Questions (Page 1)

Questions 1–5

1. 1application · medium

   A team has just completed the first draft of a state-machine model for an ATM withdrawal flow. During an informal walkthrough, a reviewer notices that the model lacks a transition for 'card retained after three failed PIN attempts'. The team lead wants to address this before formal review. What is the most appropriate next step?

   • AReject the model and restart development from scratch to ensure consistency.
   • BAdd the missing transition to the model and note it as a new iteration in the version history.
   • CUpdate the requirements document to remove the card-retention requirement.
   • DProceed with formal review and log the missing transition as a known limitation.
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2. 2application · medium

   A project has a requirement: 'The system shall lock the account after 5 failed login attempts.' The MBT model has a state 'AccountLocked' but no transition leading to it. During review, what is the most critical finding?

   • AThe model is incomplete because it does not implement the requirement's behavior.
   • BThe model is correct because the state exists even if unreachable.
   • CThe requirement is ambiguous and should be rewritten.
   • DThe model is inconsistent because the state name does not match the requirement wording.
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4. 3expert · hard

   A team is developing a model for a system with rapidly changing requirements. They are using an MBT tool that supports model versioning and diffing. The team wants to minimize the effort of re-validating the model after each requirement change. What is the most effective approach?

   • AFreeze the model and do not accept any requirement changes.
   • BUse the tool's diffing feature to identify exactly which model elements changed, and re-validate only those parts.
   • CRe-validate the entire model after every change to ensure nothing is missed.
   • DRe-generate all test cases from scratch after each change.
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5. 4application · medium

   A team has built a decision-table model for an e-commerce discount system. During validation, they execute the model against a set of historical transactions and find that the model's outputs do not match the actual system behavior for a specific combination of customer tier and order amount. What is the most appropriate first action?

   • AAssume the model is correct because it was formally reviewed.
   • BModify the model to match the system's observed behavior immediately.
   • CInvestigate whether the model or the system is incorrect by checking the requirements for that combination.
   • DDiscard the historical transactions because they are not generated from the model.
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6. 5expert · hard

   A team is reviewing a model and finds that a requirement 'R-42: The system shall send a confirmation email' is not traced to any model element. However, the team knows the system sends the email. What is the most likely explanation and the best action?

   • AThe traceability matrix is optional; ignore the missing link.
   • BThe model is missing the email-sending behavior; add it and establish the trace link.
   • CThe model is correct because the email is sent by the system, not the model.
   • DThe requirement is obsolete; remove it from the requirements document.
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