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Reasoning · 1 checks · max 800 tokens · benched 2026-09-16

Gemini 3.1 Pro Preview vs Gemini 3.8 Flash vs Gemini 3.5 Flash Lite on when does the faster train catch up?

Google models side by side on "When does the faster train catch up?": Gemini 3.5 Flash Lite scores 10/10; Gemini 3.5 Flash Lite is the cheapest answer scoring 8+ at $0.52 per 1,000 runs. Outputs, checks, judge reasons, latency and cost.

The prompt every model received

System

Think carefully, then give only the final answer in the requested format.

User

Train A leaves a station at 09:10 travelling at a constant 80 km/h. Train B leaves the same station on the same track at 09:40 travelling at a constant 120 km/h in the same direction. How many minutes after 09:10 does train B catch up with train A? Reply with only the whole number of minutes.

Rubric for the judge: The single correct answer 90, with no working shown in the final output.

Side by side

Every cell is one OpenRouter call at temperature 0 with the prompt's token cap and reasoning effort "low" where the model supports it. Cost is usage × the catalogue rate in models.json. Quality is one judge call to anthropic/claude-haiku-4.5 against the prompt's rubric, cached per prompt version.

Gemini 3.1 Pro Preview

google/gemini-3.1-pro-preview

10/10
Latency
2.9s
Cost
$0.00425
Per 1,000
$4.25

98 in · 338 out (336 reasoning) · 1 words · checks 1/1

  • exact
90

Judge: The output is exactly '90' with no extraneous commentary, matching the rubric requirement perfectly.

Gemini 3.8 Flash

google/gemini-3.8-flash

10/10
Latency
2.2s
Cost
$0.00075
Per 1,000
$0.75

98 in · 181 out (179 reasoning) · 1 words · checks 1/1

  • exact
90

Judge: The output is exactly '90' with no extraneous commentary, matching the rubric requirement perfectly.

Gemini 3.5 Flash Lite

google/gemini-3.5-flash-lite

10/10
top judge scorecheapest scoring 8+
Latency
1.1s
Cost
$0.00052
Per 1,000
$0.52

98 in · 195 out (193 reasoning) · 1 words · checks 1/1

  • exact
90

Judge: The output is exactly '90' with no extraneous commentary, matching the rubric requirement perfectly.

Frequently asked

What does this prompt test?

Reasoning: The single correct answer 90, with no working shown in the final output. The deterministic checks are exact.

Which model should I pick for this task?

If the judge's bar of 8/10 is good enough for you, Gemini 3.5 Flash Lite at $0.52 per 1,000 runs. If you need the top score, Gemini 3.5 Flash Lite at $0.52 per 1,000 runs.

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