Question 57·Hard·Command of Evidence
Battery use can limit how useful machine-learning apps are on phones. In a study of on-device image recognition, computer scientist Elena Park compared three models: TinyNet, SparseNet, and DenseNet. Park estimated each model’s efficiency by dividing its top-1 accuracy by its battery drain (measured in milliamp-hours), reasoning that a higher accuracy-per-battery value indicates a more efficient model. Park concluded that SparseNet is more battery-efficient than DenseNet.
Which choice best describes data in the graph that support Park’s conclusion?
For command-of-evidence questions tied to a graph, restate the author’s claim in measurable terms (here: higher accuracy per battery drain). Then focus only on the entities being compared in the claim (SparseNet and DenseNet) and find a graph-based relationship that directly supports that comparison, ideally using both axes rather than just one.
Hints
Focus on the comparison in the conclusion
The conclusion compares SparseNet specifically to DenseNet, so the best evidence should mention both of those models.
Use both axes
Efficiency here depends on accuracy and battery drain together. Look for a choice that connects the two quantities, not just one.
Look for “similar accuracy, different battery”
Check whether SparseNet and DenseNet have almost the same accuracy, and then compare how far apart they are on battery drain.
Step-by-step Explanation
Identify what would support the conclusion
Park’s conclusion is comparative: SparseNet is more battery-efficient than DenseNet, meaning SparseNet should have similar accuracy but lower battery drain (or higher accuracy at similar drain).
Read the graph values for the two relevant models
From the graph, SparseNet is around 92% accuracy at about 120 mAh, while DenseNet is around 93% accuracy at about 180 mAh.
Connect those values to efficiency
DenseNet’s accuracy is only about 1 percentage point higher, but it requires much more battery drain than SparseNet, so SparseNet’s accuracy-per-battery is higher.
Match the description to an answer choice
The choice that states this near-equal accuracy but much higher battery drain for DenseNet is: DenseNet drains substantially more battery than SparseNet but attains only about one percentage point higher accuracy.