Cobalt Robotics: Paid Growth Is Getting Expensive
Product Management
medium45 min0 submissionsGoogle
Scenario
Cobalt Robotics's industrial robotics product has grown almost entirely through paid acquisition. That is becoming unsustainable.
Unit economics (monthly):
- Blended CAC: $886
- ARPU: $579
- Gross margin: 70%
- Monthly churn: 5.8%
Existing referral behaviour:
- 14% of active users invite at least one other person
- 10% of those invitations convert to a signup
CAC has risen 36% over 18 months as auction competition increased. The CEO wants a growth model that does not depend on buying every user.
Supporting data
trend
- cac increase 18m pct
- 36
referral
- implied k factor
- 0.014
- users inviting pct
- 14
- invite conversion pct
- 10
unit economics
- blended cac
- 886
- arpu monthly
- 579
- estimated ltv
- 6988
- ltv cac ratio
- 7.89
- gross margin pct
- 70
- monthly churn pct
- 5.8
Your task
Design the growth strategy. Provide:
- Analysis — current unit economics, payback period, and the strength of the existing loop.
- Risks — of the loop you propose and of continuing as-is.
- Recommendation — the specific loop to build and how you would prove it works.
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How you'll be graded
100 points, 60% to pass.
- loop design25
- growth model25
- recommendation25
- quantitative reasoning25
Hint
Reveal suggested structure
- LTV = ARPU × gross margin ÷ churn.
- LTV:CAC and payback period = CAC ÷ (ARPU × margin).
- K-factor = invite rate × conversion rate. K ≥ 1 is self-sustaining; below that the loop amplifies but does not replace paid.
- Identify the loop type — viral, content, or paid-recycled.
- Find the weakest step and fix that, rather than adding a new channel.