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Capital One·Data Scientist·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Capital One Data Scientist interview that leaned heavier on business case math than I expected. The core of it was a renewable energy project comparison, basically a payback period calculation with some qualitative reasoning tacked on. Not a coding round at all, which threw me a little.

Questions Asked (1)

Q1

A company is choosing between two renewable energy projects. Solar has a $12.5M upfront cost, no variable cost, and produces 150,000 units for 75% of the year and 50,000 units for the remaining 25%, all sold at $40/unit. The other project is corn bio-power with a $2.5M upfront cost, $30/unit variable cost, constant output, and the same $40/unit price. Calculate the payback period for each project and recommend which one to pursue.

Product StrategyPricing & MonetizationTechnical Trade-offs
Author's notes

I went straight to the solar math and fumbled the weighted average production for a second.

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AI HintsAI Generated

Suggested Approach

First, calculate the annual revenue and profit for each project by carefully accounting for the variable output of solar and the variable cost of bio-power. Then compute the payback period for each and compare, but also consider qualitative factors like risk, scalability, and strategic fit before making a recommendation.

Pro tip: Don't just focus on the payback period; discuss the trade-offs between higher upfront cost with lower operating cost (solar) versus lower upfront cost with higher operating cost (bio-power), and how that impacts cash flow and risk.

1. Calculate Annual Revenue for Each Project

For solar, compute weighted average annual output: (150,000 * 0.75) + (50,000 * 0.25) = 125,000 units, then multiply by $40. For bio-power, assume constant output; if not given, you may need to infer from context or state assumptions.

2. Calculate Annual Profit for Each Project

Subtract variable costs from revenue. Solar has no variable cost, so profit equals revenue. Bio-power profit = (revenue - variable cost per unit * output).

3. Compute Payback Period

Divide the upfront cost by annual profit for each project. This gives the number of years to recover the initial investment.

4. Compare and Recommend

Compare payback periods, but also consider other factors like risk, maintenance, scalability, and strategic alignment. Recommend the project with the better overall profile, not just the shortest payback.

Key Points to Mention

  • Weighted average calculation for solar output due to varying production.
  • Assumption about bio-power constant output: if not specified, state that you assume it operates at full capacity year-round or clarify.
  • Payback period formula: upfront cost / annual cash flow.
  • Qualitative factors: solar has higher upfront cost but lower operating cost and no variable cost, leading to higher long-term profitability; bio-power has lower upfront cost but higher variable cost, making it less profitable at scale.
  • Risk considerations: solar output variability might affect revenue, but bio-power depends on feedstock prices and supply chain.
  • Strategic fit: consider company's sustainability goals, available capital, and risk tolerance.

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