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Zoox·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Basic reasoning screen for a Data Engineer role at Zoox. Two questions, nothing technical in the traditional sense, more like a sanity check on whether you can think through simple problems out loud.

Questions Asked (2)

Q1

Why is summer generally hotter than winter?

Adaptability & Ambiguity
Author's notes

Seemed too easy and I almost overthought it.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the scope: are we discussing Earth's seasons or a general principle? Then explain the axial tilt effect, emphasizing that it's about the angle of sunlight and day length, not distance from the sun. Use simple, clear language and connect it to how you'd approach ambiguous problems.

Pro tip: Acknowledge common misconceptions (like distance from the sun) and explain why they're wrong; this shows you can identify and correct flawed assumptions, a key skill in ambiguous situations.

1. Clarify the question

Ask if the question refers to Earth specifically or a general planetary scenario. This demonstrates you don't assume and seek to understand the problem space.

2. Address common misconception

Mention that many think it's due to Earth's distance from the sun, but actually Earth is closest to the sun in January (Northern Hemisphere winter). This shows you can debunk myths.

3. Explain the axial tilt

Describe how Earth's 23.5-degree tilt causes sunlight to hit at a more direct angle in summer, concentrating energy, and at a shallower angle in winter, spreading energy.

4. Include day length

Note that summer has longer days, giving more time for the sun to heat the surface, while winter has shorter days.

5. Summarize and connect to role

Summarize that axial tilt and day length are the main factors, and relate this to how you'd analyze ambiguous problems by breaking them down and testing hypotheses.

Key Points to Mention

  • Earth's axial tilt (23.5 degrees) is the primary cause of seasons.
  • Angle of sunlight: more direct in summer, more spread out in winter.
  • Day length: longer days in summer, shorter in winter.
  • Misconception: distance from the sun is not the main factor (Earth is actually closer in Northern Hemisphere winter).
  • The effect is opposite in the Southern Hemisphere.
  • This illustrates how to approach ambiguous problems: clarify, identify assumptions, and reason from first principles.

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

Q2

If you invest $1,000 at a 100% annual interest rate, compounded once per year with no withdrawals, how much will you have after 20 years?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This is just 1000 times 2 to the power of 20, which is a little over a billion dollars.

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AI HintsAI Generated

Suggested Approach

Recognize this as a compound interest problem and apply the formula A = P(1 + r/n)^(nt). Since interest is compounded annually, n=1, so the amount after 20 years is $1,000 * (2)^20 = $1,048,576,000. Clearly state the formula, plug in the values, and compute the result.

Pro tip: Mention that this is a classic example of exponential growth, and note that if compounding were more frequent (e.g., continuously), the amount would be even larger, approaching $1,000 * e^20 ≈ $485,165,195, but here it's annual compounding so it's exactly $2^20 * 1000.

1. Identify the problem type

Recognize that this is a compound interest calculation with annual compounding, not simple interest.

2. Recall the compound interest formula

Use A = P(1 + r/n)^(nt), where P is principal, r is annual interest rate, n is number of times compounded per year, and t is time in years.

3. Plug in the given values

Substitute P = 1000, r = 1.0 (100%), n = 1, and t = 20 into the formula to get A = 1000 * (1 + 1/1)^(1*20) = 1000 * 2^20.

4. Compute the result

Calculate 2^20 = 1,048,576, then multiply by 1000 to get $1,048,576,000.

5. Sanity check and contextualize

Verify the magnitude: doubling each year for 20 years yields about 1 million times the initial amount. Optionally, mention the effect of compounding frequency.

Key Points to Mention

  • Compound interest formula: A = P(1 + r/n)^(nt)
  • Annual compounding means n=1, so the formula simplifies to A = P(1 + r)^t
  • 100% interest rate means r=1, so the base becomes 2
  • Exponential growth: doubling each year for 20 years results in 2^20 = 1,048,576 times the principal
  • The final amount is $1,048,576,000 (over $1 billion)
  • Contrast with simple interest, which would yield only $21,000 after 20 years

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