McKinsey Problem Solving Test – PST

Question:

I am trying to prepare for the Problem Solving Test portion of McKinsey's interview process and am not sure how to structure my practice strategy.  Are you familiar with it?  I am a law school graduate and have taken business law classes and had business law internships but have no serious business background.

I want to be as prepared as possible for the Problem Solving Test and case interviews.  I have less than a week to prepare but I have been studying the practice Problem Solving Test on the website for the past couple of days.

I ordered Case In Point by Marc Consentino (recommended by a current McKinsey employee) and will begin to use it today.  Though the Problem Solving Test is not difficult, it requires business savvy and comfort with numbers.

I think the Problem Solving Test is a milder written version of case questions but I am not familiar with the case method.  Any suggestions on how can I strengthen my business judgment in the upcoming days?    Any guidance would be greatly appreciated.

My Response:

The McKinsey Problem Solving Test is really a case interview where much of the data has already been gathered for you. In a typical case interview, you start with no data and the candidate is expected to determine what kind of data would be relevant and then asking for it.

The McKinsey Problem Solving Test provides much of this data in advance, and is asking you which conclusions CAN mathematically and logically be drawn from the data. Similarly, it also test what conclusions can NOT be mathematically and logically drawn from the data.

The McKinsey PST does not require business savvy in order to perform well on the test. The test is written to be accessible to people with non-business backgrounds and from a variety of countries/cultures.

It is primarily a math, estimation, logic test, and critical thinking test.

It's actually fairly reflective of the day-to-day work of a consultant — looking at a bunch of data and determining what conclusions you can present to a client based on the data.

I think the fact that you're not permitted to use a calculator is interesting.

Given all the computations one could do, there probably isn't enough time to run every computation on there. You have to "ballpark-it" and do a lot of applied estimations.

The only other tip I would suggest is to read the question carefully.

Confession: The first time I took a shot at the first four questions on the sample test… and I missed two of them! (Granted, at the time I had a 3-week-old newborn in the house and am sleeping three hours a night, but still… pretty poor performance considering I got perfect math scores on my college entrance exams.)

My mistakes were basically careless errors.

I didn't read the question carefully, or I glossed over the labels in charts and made the assumption of what data I thought it covered, without actually looking at the labels carefully to see literally what it covers.

In some respects, having some business background can be a bit of a liability. Someone with an analytical and logical bent will take the questions and the data literally — which is good.

Someone like me in a rush is tempted to rush to a conclusion, notice a familiar data format (and assume I know what's being explained), and quickly attempt to answer the question I think is being asked using the data I think is being presented… rather than answering the LITERAL question being asked using the actual data being presented.

There are three ways to prepare for the McKinsey Problem Solving Test.

First you can take sample tests from McKinsey and some of the other firms who use a similar process. The upside is these are the most realistic representations of what to expect on the real test. The downside is there are very few sample tests available online. So you will likely go through all of them very quickly.

The second approach is to practice some of the fundamental skills that the McKinsey Problem Solving test evaluates.

The main ones are math "word problems" — starting with a verbal description of a situation and having to figure out which math computation is or is not required given what is asked. This general skill is very useful on the job as a consultant.

The second is data interpretation — you have all this data in terms of charts, graphs, data tables, what does all this data mean? What data is actually necessary to answer the question? What data is really just a distraction?

For this second approach, I recommend using GRE practice tests (only a subset of the questions) as they do a pretty good job of helping you improve those skills. By the way, I think these math / numerical critical reasoning skills are like a muscle. The more you use it, the better you get.

When I took standardized tests many years ago, I got a perfect score on every math test I took. Yet, when I look at some of the GRE practice questions, my brain literally hurts. I have not had to use those particular skills in a long time (a client has never asked me to take a multiple choice test) and I find that part of my brain getting a good workout.

Note the math / numerical critical reasoning / data interpretation practice resources help with only 50% – 70% of the test. So it does not cover the whole McKinsey Problem Solving Test.

But I think the way I would characterize this preparation approach is to get very efficient (from a 'how long it takes you to answer a question like this') so that you have more time to think about how to answer the questions on the test that are not strictly a math question.

These questions usually involve building upon your answers to multiple math / data interpretation type questions and figuring out the significance of it all (e.g., what is the big picture, what is the business conclusion to draw from this, how do you interpret your answers to the last three questions, etc…)

The third method is to practice the speed and accuracy of your arithmetic. The McK PST is a TIMED test. This is not the kind of math test designed to test the entire population of people with a wide range of math skills. It is intended to identify only those who are very good at math, logical thinking, etc… If you are really good at math, you will finish the test BARELY.

So even if you have a PhD in Physics or Math (I'm being serious on this), it is VERY IMPORTANT you practice your math computations. I get many, many emails from engineers who had 4.0 gpa's in school who did not pass the PST. Your math skill is a muscle. The more you use it, the stronger it gets.

Included below are links for resources for both preparation approaches.

Links for Problem Solving Test Samples:

• McKinsey Problem Solving Test – Sample Test Question on Data Sufficiency (from this website)
• McKinsey Problem Solving Test – Example Test Question on Data Sufficiency – Answer Guide (from this website)
• McKinsey Problem Solving Test Sample (from McKinsey Website)
• McKinsey Problem Solving Test – Practice Test Answer Key & Explanations
• McKinsey Problem Solving Test – 2001 Version (no longer used, but has similar questions)
• Monitor Group's Problem Solving Test – Sample
• Sample Test from 20/20 (Consulting Firm Started by Ex-McKinsey Consultants)

The Problem Solving Test is principally a critical reasoning and data interpretation test. People with strong math backgrounds tend to do well on this test. If you come from more of a liberal arts background and need to practice both your math and data interpretation skills, the following resources are helpful for both the McKinsey Problem Test, any type of 1:1 or group case interview involving a written document (usually with charts and tables).

Data Interpretation & Word Problem Practice Resources:

• Kaplan GRE Exam Math Workbook (Copyright 2008)- Chapter 2 Arithmetic Review (if you're really rusty on math), Chapter 6 – Word Problem Practice, Chapter 7 – Data Interpretation Practice
• Nova's GRE Math Prep Course (Copyright 2010) – Percents (page 330-346), Graphs (pages 347 – 375), Word Problems (pages 376 – 396) [If you're really rusty on math: Averages (pages 274 - 284), Ratio & Proportions (pages 285 - 303)
• Cliff Notes Math Review for Standardized Tests (2nd Edition, Copyright 2010) - Word Problems Review (pages 318 - 362, but excluding the section on Geometry pages 347 - 350)

The three practice resources above are listed in order of their usefulness. Also full disclosure-- those links are Amazon affiliate links, which means if you click on those links and buy something, my company earns a fee (a whopping $0.50 or something like that).

Arithmetic Speed & Accuracy Practice

• www.CaseInterviewMath.com- This is math practice tool that I developed for practicing: 1) arithmetic for speed and accuracy (both VERY important on the McKinsey PST) and 2) estimation math with large numbers (useful for solving some of the McKinsey PST word problems faster where precise math isn't necessary to answer the question, just an estimate will suffice.)This tool compares your math accuracy and speed to other CaseInterview.com members and to my own test results. This will help give you an idea of how your math skills compare with others.

Additional Comment #1 (From a Reader)

The following comments are from one of my newsletter readers who took and passed the actual McKinsey Problem Solving Test.  (By the way, just click the following link to receive my case interview preparation tips newsletter)

The actual test does not match the practice test in terms of level of difficulty, but it cannot be said that it is harder.

Some questions are harder, some are easier than those given in the practice test. But the practice test gives you a feel of the type of questions and timing.

I did a few things in particular to prepare that I thought would be useful, however they were more about the attitude than actual preparations for the test:

In terms of preparations, I only solved the practice test and then compared my answers to the correct ones. Then I worked out the wrong answers slowly to realize where did I go wrong.

When it comes to the attitude, it is important to go to the test with a positive attitude but with the expectation that very few are those who actually make it.

Going with a "Why-not; let's take a shot" attitude will alleviate a good portion of the stress associated with the tight timing and will allow the candidate to think clearly.

Now here are some additional insights about the PST:

For business or economics students, just practice the sample and mind the time, you know the rest. (This is my own experience as a business graduate)

For non-business students, brush up on few quantitative business concepts before going to the test, it is said that it does not require a business knowledge, but definitely some business sense and acumen.

Stress will definitely play against you, RELAX the test can be completed in the allotted time, don't worry about it.You will be marking the 26th answer by the end of the last minute though.

Make sure you complete all questions, there are no penalties; but this we know. What we don't know is, even when you are taking a question as a guess, the test is tailored such as it will allow you to take an informed guess which is correct; so use elimination and educated guesses to your advantage.

When it comes to the attitude:

Very few people get into McKinsey, put this information into perspective and go to the test in a 'Game' frame of mind, enjoy it; it is nice and stimulating.

Relax, breathe before starting the test and remember if you made it so far and your consulting resume caught McKinsey's accurate eye, it means you mostly have what it takes to pass.

Do not stress about the outcome of the test once you leave the room. Mckinsey will get back to you shortly; they have the best recruitment system in the world and they do not make people wait, I know people who knew the outcome as early as 24 hours after the test.

A great thing that is a MUST-KNOW about McKinsey, they do not select the top x% performers. They have a cut-off score, if you pass it, you're in for the interview process; you're not competing against anyone, you're only invited to stretch your own potential.

One last note I would like to add, you will get out of the McKinsey process feeling great, whatever the outcome is. These people are amazing, this company is extremely professional; and they make you feel appreciated and respected at every stage of the recruitment process, whether you make it or not. So my point: get the best out of it for yourself.

Additional Comment #2: (From a Reader)

Note: Concerning the PST test, I found that the best way to get the answer for a question is by applying a similar analysis to a case interview. That is, when asked about something, the best way is to actually think of a hypothesis and what kind of data is needed to give the answer. And then look for the data in the text. I found that pretty useful. I felt like sharing this as a tip.