Ecosystem Builder
Build a sustainable food chain across complex terrain — or let the Solver do it for you in under 10 minutes. Two products, one goal: ace the Ecosystem scenario.
What is the Ecosystem Builder?
The Ecosystem Builder is a simulation scenario in McKinsey’s Solve assessment. You act as an environmental researcher tasked with constructing a sustainable food chain across a specific terrain. Your goal is to select a set of species that can survive together — each predator must have enough prey to meet its calorie requirements, every predator-prey pair must produce a calorie surplus, and all species must be compatible with the terrain and climate conditions of the site.
The difficulty comes from cascading constraints: a predator consumes whichever prey provides the greatest number of calories first, so the order and composition of your food chain affects the entire system. A single miscalculation collapses the ecosystem. Candidates need to hold multiple rules in mind simultaneously, under time pressure, without making an arithmetic error.
The rules
When multiple prey species offer the same calorie value, the predator consumes them equally. The ecosystem is only valid when every pair in the chain has a calorie surplus and every species is terrain-compatible. Verifying this manually is slow and error-prone — which is exactly why the Solver exists.
Why candidates struggle
Two ways to prepare.
Whether you want to understand the scenario deeply through practice or guarantee your score with the Solver, we have you covered.
Solve it in under 10 minutes.
Enter your food chain and the Solver checks calorie balance and terrain compatibility instantly — eliminating the risk of manual errors.
- Solve the Ecosystem scenario in < 10 minutes
- Instant calorie & terrain validation
- Eliminates risk of calculation errors
- Simple web interface — no download required
- Instant access
Build your understanding from scratch.
Three full Ecosystem simulations built from real past PSG data, with detailed solutions for every question.
- 3 × full Ecosystem simulations
- Real past PSG data
- Detailed solutions for every question
- Exact game replication
- Instant access
Both products are included in the Ultimate PSG Bundle — the best-value way to prepare for the full assessment.