McKinsey Redrock: the complete guide to the study and the cases
In this guide
What Redrock is
Redrock (McKinsey writes it Red Rock Study) is one of the games in McKinsey Solve, the online assessment McKinsey sends after you apply. It is the most consultant-like of the games. You get a research objective about a fictional island ecosystem, a few paragraphs of notes and one or two data tables. Your job is to pull out the facts the objective needs, calculate what it asks for, and fill in a short report with your results and the right chart.
After the study come six standalone cases. Each has its own short exhibit and one question: a calculation, a ratio, a percentage change, or a judgement about what the data supports. They do not build on the study or on each other, so a mistake in one case costs you that case only.
Redrock replaced the older Ecosystem and Plant Defense games, and since Ecosystem dropped out of invitations it has been one of the two games every candidate plays, alongside Sea Wolf. Longer invitations add the Sustainable Futures Lab. The 2026 changes guide tracks the line-up as it moves.
The 35-minute clock
The whole game runs on one 35-minute clock. There is no separate timer for the study and the cases, so every minute you spend in the investigation is a minute you no longer have for the cases at the end. The split below is a sensible plan, built from candidate reports and our own timed runs; it is not a rule the game enforces.
| Stage | What you do | Plan for |
|---|---|---|
| 1. Investigation | Read the objective, the notes and the exhibits; drag the facts you need into the research journal | About 5 minutes |
| 2. Analysis | Answer three or so calculation questions, some with several parts, using the journal and the on-screen calculator | About 12 minutes |
| 3. Report | Fill the blanks in a short written summary and choose the chart that fits the data | About 5 minutes |
| 4. Six cases | Answer six standalone questions, each with its own exhibit | About 2 minutes each |
| Buffer | A last check of anything you flagged | About 1 minute |
The clock keeps running through the transitions, and candidates consistently say the cases are where time runs out. If you are behind at the report, finish it quickly and move on: six cases at two minutes each is a fixed cost you cannot compress much.
Stage 1: Investigation
The investigation opens with the research objective. Read it twice before anything else, because it tells you exactly which numbers the rest of the study will need. Below it sit the notes (a few paragraphs with key figures marked) and one or more exhibits. You collect a fact by dragging it into the research journal, a panel that holds everything you will use in the analysis.
The notes always include facts the objective does not need. That is deliberate: part of what the stage measures is whether you can tell a relevant number from a nearby one. Collecting everything wastes time now and clutters the journal later, when you are hunting for the right figure under pressure.
Worked example: what goes in the journal?
Objective: Researchers want to know how the 2,500-hectare Aster Marsh divides between reed beds, open water and mudflat in year 4, and whether Bed A's reeds grew faster from year 1 to year 4 than the three reed beds combined.
Notes: Aster Marsh covers 2,500 hectares of Redrock Island's east coast. Open water makes up two-fifths of the marsh, and the rest is reed beds and mudflat. Fourteen species of wading bird nest on the marsh. Rainfall last year was 860 mm, a tenth above the ten-year average. A survey team of six visits each spring.
| Reed bed area (hectares) | Year 1 | Year 2 | Year 3 | Year 4 |
|---|---|---|---|---|
| Bed A | 320 | 345 | 370 | 400 |
| Bed B | 280 | 285 | 295 | 300 |
| Bed C | 200 | 215 | 235 | 260 |
Show the facts to collect
Collect 8 facts
- The marsh's total area, 2,500 hectares, and the open-water share, two-fifths. Together they give open water and, by subtraction, mudflat.
- Year 1 and year 4 for each bed: 320 and 400, 280 and 300, 200 and 260. The objective compares year 1 with year 4, so these six numbers answer it.
- Leave out the birds, the rainfall, the survey team, and the year 2 and year 3 columns. None of them is in the objective.
The trap: the rainfall figure looks like data, and "a tenth above average" invites a calculation. The objective asks about area, so it is noise. If a later question did need it, you could go back for it; collecting it now only slows you down.
Stage 2: Analysis
The analysis asks a handful of calculation questions, usually three, some with several answer boxes. You drag facts from the journal into the calculator or type them, and the result goes into the answer box. The questions follow the objective closely, so if you collected the right facts, every number you need is already in the journal.
Expect the arithmetic of a business case: shares of a total, percentage change, growth over several years, averages and simple ratios. Two conventions catch people out. "Growth from year 1 to year 4" covers three years of change, not four. And "average annual growth, not considering compounding" means total growth divided by the number of years, not the compound rate.
Worked example: the year 4 areas
Using the Aster Marsh facts above, how many hectares are reed beds, open water and mudflat in year 4?
Show answer and method
Answer 960 · 1,000 · 540
- Reed beds: 400 + 300 + 260 = 960 hectares.
- Open water: two-fifths of 2,500 = 1,000 hectares.
- Mudflat is the rest: 2,500 − 960 − 1,000 = 540 hectares.
Check it: the three areas should add back to the total. 960 + 1,000 + 540 = 2,500. A ten-second check like this catches most dragging errors before they spread into the report.
Worked example: which grew faster?
Did Bed A grow faster from year 1 to year 4 than the three beds combined? And which bed had the highest average annual growth rate, not considering compounding?
Show answer and method
Answer Yes: 25% against 20%. Bed C, at 10% a year
- Bed A: (400 − 320) ÷ 320 = 80 ÷ 320 = 25%.
- All three beds: year 1 total 800, year 4 total 960, so (960 − 800) ÷ 800 = 20%. Bed A grew faster.
- Average annual growth is total growth divided by three years. Bed A: 25% ÷ 3 = 8.3%. Bed B: 20 ÷ 280 = 7.1%, so 2.4% a year. Bed C: 60 ÷ 200 = 30%, so 10% a year.
Two traps: dividing by four years instead of three gives 7.5% for Bed C. And Bed A added the most hectares (80) but Bed C grew fastest in percentage terms because it started smallest. Read whether the question asks about hectares or rates.
Stage 3: Report
The report is not an essay. You get a short paragraph summarising the study, with eight to ten blanks to fill: numbers you have already calculated and words chosen from dropdowns (which bed, which land type, higher or lower). Then you choose the chart that fits one part of the data. Candidates report that once you confirm the report, you cannot go back to the earlier stages, so check it before you confirm.
If your analysis was right, the report is quick: most blanks are numbers you already have. The marks you can lose are in the dropdowns, where the paragraph's wording decides the answer, and in the chart choice.
Worked example: fill the blanks, pick the chart
"In year 4, [1] covers more of Aster Marsh than any other land type, at [2] hectares, followed by the reed beds at [3] hectares. From year 1 to year 4, Bed A grew by [4]%, [5] than the three beds combined." Then choose the chart for how the marsh divides in year 4: a bar chart, a line chart or a pie chart.
Show answer and method
Answer [1] open water, [2] 1,000, [3] 960, [4] 25, [5] faster. Pie chart
- Open water (1,000 ha) is larger than the reed beds combined (960 ha), so it fills blank 1, even though "reed beds" is the subject of most of the study.
- The growth blanks come straight from the analysis: 25%, and faster than the combined 20%.
- The chart shows one point in time split into parts of a whole (40% open water, 38.4% reeds, 21.6% mudflat), which is what a pie chart is for.
The chart rule: parts of a whole at one moment, pie. A trend across years, line. Separate categories compared side by side, bar. Read what the chart prompt says it must show, not what the study is mostly about.
Stage 4: The six cases
The cases are six short questions, each with its own small exhibit, usually a table. They test the same arithmetic as the analysis, plus some questions about what the data supports. Because each case stands alone, a slow or wrong case does not damage the next one, which is why moving on from a stuck case is the right call.
Common shapes: a "what if" (if one figure doubled, what would the share or average become), a ratio between two groups, a percentage of a total, an average of several changes, and "which of these research questions does the data support". Read the question before the exhibit, so you know which row or column you need.
Worked example: a "what if" case
A seed trial plants three seed types in sand and clay. If the number of Type B seeds planted in clay doubled and their germination rate stayed the same, what share of all germinated seeds would be Type B? Give one decimal place.
| Seeds (planted / germinated) | Sand | Clay |
|---|---|---|
| Type A | 200 / 120 | 100 / 45 |
| Type B | 150 / 60 | 100 / 70 |
| Type C | 50 / 40 | 100 / 30 |
Show answer and method
Answer 46.0%
- Today 365 seeds germinate in total: 120 + 45 + 60 + 70 + 40 + 30.
- Doubling Type B in clay doubles its germinated seeds from 70 to 140, adding 70 to the total: 435.
- Type B now has 60 + 140 = 200 germinated seeds. 200 ÷ 435 = 46.0%.
The trap: dividing 200 by the old total of 365 gives 54.8%. When a "what if" changes one cell, it changes the total too.
Worked example: what does the data support?
Using the same seed table, which statements does the data support? (a) Type C germinates better in sand than in clay. (b) Clay raises germination for every seed type. (c) Type A was planted more than any other type. (d) Germination depends on rainfall.
Show answer and method
Answer (a) and (c)
- (a) Type C germinates at 80% in sand (40 of 50) and 30% in clay (30 of 100). Supported.
- (b) Clay helps Type B (70% against 40%) but hurts Types A and C. Not supported.
- (c) Type A: 300 planted, Type B: 250, Type C: 150. Supported.
- (d) The table has no rainfall data, so it can neither support nor reject this.
The rule: a statement is supported only if this table shows it. Plausible is not the same as supported, and "every" or "always" fails on a single counter-example.
How Redrock is scored
McKinsey does not publish how Redrock is marked. What candidates and coaches agree on is that your answers carry the weight: the numbers you enter in the analysis and the cases, the words you choose in the report, and the chart. A number needs to match the correct answer to the rounding the question asks for, so follow the stated units and decimal places.
Prep sites often say Solve also scores your process, such as which facts you collected and how directly you worked. McKinsey describes Solve as measuring how you solve problems as well as the result, but it has not said what signals it uses, so treat process scoring as likely but unspecified. Either way, the habits that help are the same: collect what the objective needs, work in a straight line, and do not change answers at random.
Your Redrock result combines with your other games into one Solve score. Recruiters will usually share the score and its decile if you ask; see the scoring section of the Solve guide for what candidates report about those numbers.
Where candidates lose marks
Most lost marks in Redrock come from a short list of habits, not from hard maths. Each one below is a pattern that candidates describe again and again after the test, and each has a simple fix.
| Mistake | What it looks like | The fix |
|---|---|---|
| Reading everything | Ten minutes in the investigation, every paragraph read closely | Read the objective first and skim the notes for the nouns it names |
| Collecting everything | A journal of twenty facts, half of them noise | Collect only what a question in the objective needs; you can go back |
| Counting years wrongly | Year 1 to year 4 treated as four years of growth | Count the gaps between years, not the years |
| Compounding when told not to | A compound annual rate where the question says "not considering compounding" | Total growth divided by the number of years |
| The old denominator | A "what if" share divided by the original total | Change the total whenever you change a part of it |
| Units and rounding | Hectares where the box wants a percentage, or the wrong number of decimals | Read the box's label and the rounding instruction before you type |
| The chart by habit | A bar chart chosen because the study was about comparison | Read what the chart prompt asks it to show |
| Stuck on one case | Four minutes on case two, cases five and six guessed | Two minutes, your answer, move on |
Two of these deserve a word more. The year count catches strong candidates because it is the kind of thing you get right on paper and wrong at speed; say "three gaps" to yourself every time you see two years. And the stuck case is a decision, not a skill: candidates who finish all six cases nearly always do better than candidates who perfect four. If the clock shows under twelve minutes when you reach the cases, you are already behind and should answer the easy ones first.
The calculator brings its own risk. Dragging a figure from the journal is quicker than typing it, but it is easy to drag the wrong row when two figures sit side by side. Glance at the number in the calculator before you press equals. A check of one second saves the whole chain of answers that depends on it.
How to prepare
- Learn the stages before you practise them. Knowing that the report is fill-in-the-blanks and the cases are standalone changes how you spend the clock. This guide and one timed run will teach you more than a week of general maths drills.
- Practise reading objectives. For any business chart you see, write one line saying what question it answers and which two or three numbers you would need. That is the investigation skill.
- Drill the four calculations. Share of a total, percentage change, average annual growth without compounding, and ratios. Our Solve tips cover the shortcuts.
- Learn the chart rule. Parts of a whole: pie. Change over time: line. Categories side by side: bar.
- Run the whole game against the clock. The Redrock Simulation runs the study and six cases on a 35-minute clock with a scored report, across several scenarios, so you can practise the time split rather than just the maths.
- Set a case rule. If a case is not moving after two minutes, enter your answer and go on. One lost case costs less than three rushed ones.
Frequently asked questions
How long is the Redrock game?
35 minutes on one clock, covering the study (investigation, analysis and report) and the six cases. There is no separate timer for each stage. A sensible plan is about 5 minutes for the investigation, 12 for the analysis, 5 for the report and 2 for each case.
Is there a calculator in Redrock?
Candidates report an on-screen calculator from the analysis stage onwards, which takes figures from the research journal. McKinsey's own material does not mention it, so be ready to do simple sums by hand or on paper as well.
Do you write the Redrock report yourself?
No. The report is a short paragraph with eight to ten blanks, filled with your calculated numbers and with words chosen from dropdowns, followed by a choice of chart. There is no free writing.
Can you go back to earlier stages?
Within the study you can move back to check facts, but candidates report that confirming the report locks the study. Check the report before you confirm it. The six cases come after.
How many cases are there after the study?
Six, each with its own exhibit and question. They do not depend on the study or on each other. Some older accounts mention more cases, but current invitations report six.
What maths do you need for Redrock?
Shares of a total, percentage change, average growth over several years without compounding, ratios and simple averages. There is no statistics or algebra. What makes it hard is doing these quickly and accurately against the clock while choosing which numbers to use.
What if I run out of time before the cases?
A blank case cannot score, so a quick answer is worth more than leaving it empty. If you are short of time, read each case's question first, answer the ones you can do in under a minute, and come back to the rest if time allows.
Is Redrock on every McKinsey Solve invitation?
On current invitations, yes. Every format reported in 2026 (65, 85 and 95 minutes) includes Redrock and Sea Wolf; the longer ones add the Sustainable Futures Lab.
Sources (3)
- PrepLounge forum, "McKinsey - Solve Game" (2025): candidate accounts of Redrock timing and coach advice on unfinished reports. preplounge.com
- r/ConsultingAndFinance, Redrock threads (2024 to 2026): candidate reports on the stages and on where time runs out. reddit.com
- Ace the Solve, Redrock Simulation: our timed reconstruction of the study and cases, used for the time split and the worked-example formats. acethesolve.com