McKinsey Red Rock
A haul-fleet exhibit you can actually read
Calderas Mining: diesel $2.4m opex versus electric with a 22% save and $1.1m capex. Four questions, ten-minute clock, calculator on the page. Independent. Not affiliated with McKinsey.
How to structure the math
Red Rock is research-and-calculate. Write the identity, keep capex and opex in the same units, amortize only if asked, then say whether the payback is fast enough to care.
- Equation. Electric opex = diesel × (1 − save). If they amortize, add capex / life to opex before you call it a save.
- Units. $m opex versus $m capex. Do not treat a 22% save as dollars.
- So-what. Is 3.6 years fast for a haul fleet that lasts past five? That is the recommendation, not the 0.308.
“Diesel opex is $2.4m. A 22% cut leaves electric opex at $1.87m. Capex $1.1m over five years is $0.22m a year, so fully loaded electric is $2.09m — a $0.31m net save. Payback on that net is about 3.6 years. I would take it if the trucks last well past five.”
Usual miss. Amortizing when the question did not ask, or skipping amortization when it did. Also: quoting 22% as if it were dollars.
Timed sampler
Calderas Mining haul fleet
Diesel $2.4m opex. Electric: 22% opex save, $1.1m capex over 5 years. Four questions, forward-only.
10:00 left
| Item | Diesel | Electric |
|---|---|---|
| Annual opex | $2.4m | 22% lower |
| Capex | — | $1.1m / 5 years |
Q1/4
Diesel haul opex is $2.4m a year. Electric cuts opex 22%. What is annual electric opex, in $m, before capex?
Calculator
Four-function. Estimate first.
0
What this sampler is
A short stand-in for the research-and-calculate feel of Red Rock. Solve is three named games, not one combined simulator. The other two are Sea Wolf and SFL.
FAQ
Is this the real McKinsey Red Rock game?
No. Original independent practice in the same skill family: read an exhibit, do the math, name the so-what. Formats vary by office.
Why is there a calculator?
The live game is numerical. Use the keypad for arithmetic after you write the equation. Capex amortization is the usual miss.