New PMP Question & Answers with explanation

Projects operating in agile environments where a high degree of uncertainty exists and where the scope is not yet fully defined, may not benefit from detailed cost calculations due to frequent changes. Instead, lightweight estimation methods can be used to generate a fast, high-level forecast of project labor costs, which can then be easily adjusted as changes arise. Detailed estimates are:
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Kevin is assigned to a software development project that will start in the near future and is currently tailoring the PMBOK processes to satisfy the project’s specific needs. Kevin wants to introduce a new process, “Identify Key Deliverables”, to the existing six project scope management processes. Although he understands that project deliverables identification is already in the PMBOK scope management processes, he believes that having a dedicated process will stress the importance of determining and agreeing to key project deliverables. The best position for the new “Identify Key Deliverables” process should be between which of the following two processes?
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The output of the Validate Scope process is accepted deliverables that are formally signed off by the stakeholders. The stakeholders, on some projects, can get involved with the project as early as:
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Which of the following defines the total scope of the project and represents the work specified in the current approved project scope statement?
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Recently, a junior team member has challenged the project management approach since not all requirements identified during the Collect Requirements process were documented in the project scope statement. You are the project manager, what should you do first?
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