← Google Interview Insights

Google·Product Manager·Onsite - Product Sense / Strategy·Intermediate

Intermediate
Apr 2026

Summary

Interviewed for a PM role at Google and got hit with an estimation question about daily breaths. Pretty standard product sense / analytical warmup type of thing.

Questions Asked (1)

Q1

Estimate how many breaths a person takes in a single day.

Product Analytics & Metrics
Author's notes

I blanked for a second and then just started anchoring on breaths per minute.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Break the problem into two parts: breaths per minute and minutes per day. Start with a reasonable estimate for breaths per minute at rest, then adjust for activity levels throughout the day, and finally multiply by the number of minutes in a day.

Pro tip: State your assumptions clearly and round numbers to make calculations easier. Acknowledge that this is a rough estimate and that the exact number may vary, but the process demonstrates structured thinking.

1. Clarify the question

Confirm that the question asks for an average person over a full day, including all activities. This ensures you're solving the right problem.

2. Estimate breaths per minute

Use a known baseline: average resting respiratory rate for adults is about 12-20 breaths per minute. Choose a round number like 15 for simplicity.

3. Account for activity levels

Break the day into segments (e.g., sleep, sedentary, light activity, exercise) and assign different breathing rates to each. For example, sleep: 12 bpm, sedentary: 15 bpm, exercise: 30 bpm.

4. Calculate weighted average

Multiply the breathing rate for each segment by the hours spent in that segment, sum them up, and divide by 24 to get an average breaths per minute over the day.

5. Multiply by minutes in a day

Multiply the average breaths per minute by 1440 (minutes in a day) to get the total daily breaths. Round to a sensible number.

Key Points to Mention

  • Average resting respiratory rate for adults (12-20 breaths per minute)
  • Variation in breathing rate due to activity level (sleep, exercise, etc.)
  • Number of minutes in a day (1440)
  • Assumptions made and their impact on the final estimate
  • Rounding and simplifying calculations for ease
  • Sanity check: compare with known benchmarks (e.g., typical daily breaths ~20,000)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.