The correct answer is to reduce the number of replicas to increase GPU utilization per instance. This approach directly addresses the core issue of underutilized hardware: with GPU utilization hovering around 30% across ten replicas, you are paying for idle compute capacity. By consolidating the workload onto fewer, more fully utilized instances, you maintain the same throughput while eliminating unnecessary infrastructure costs. On the Google Professional Machine Learning Engineer exam, this scenario tests your understanding of Vertex AI’s autoscaling and resource optimization, often appearing as a trap where candidates mistakenly suggest upgrading the GPU type or adding more replicas. The key insight is that low GPU utilization signals over-provisioning, not underpowered hardware. A useful memory tip is “30% utilization means you’re paying for 70% waste—shrink the fleet, not the chip.”
PMLE Serving and scaling models Practice Question
This PMLE practice question tests your understanding of serving and scaling models. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You have a model that requires GPU for efficient inference. You deploy it on Vertex AI with a single NVIDIA T4 GPU accelerator and notice that the GPU utilization hovers around 30%. The endpoint has 10 replicas. What is the best way to improve cost efficiency while maintaining throughput?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Reduce the number of replicas to increase GPU utilization per instance.
If GPU utilization is low, you can reduce the number of replicas or increase the batch size per request to fully utilize the GPU. Reducing replicas directly saves cost. Increasing batch size may also help but requires code changes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use a larger GPU like V100 to process requests faster.
Why it's wrong here
More powerful GPU may further underutilize and cost more.
✓
Reduce the number of replicas to increase GPU utilization per instance.
Why this is correct
Fewer replicas with same traffic will increase GPU utilization and reduce cost.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable autoscaling to increase the number of replicas.
Why it's wrong here
More replicas would lower utilization further.
✗
Switch to a CPU-only instance; the model can run on CPU.
Why it's wrong here
GPU was chosen for a reason; CPU may not meet latency SLA.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which PMLE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Serving and scaling models — This question tests Serving and scaling models — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Reduce the number of replicas to increase GPU utilization per instance. — If GPU utilization is low, you can reduce the number of replicas or increase the batch size per request to fully utilize the GPU. Reducing replicas directly saves cost. Increasing batch size may also help but requires code changes.
What should I do if I get this PMLE question wrong?
Identify which PMLE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This PMLE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PMLE exam.
Question Discussion
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