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Looking for some good case interview math practice? This McKinsey case will do that for you!

Case Prompt

Your client is a seller of car lubricant. It has historically made significant profits, but recently it has come under threat. We have been hired to address three concerns.

  1. In the past, consumers believed that they needed to change their oil every 10,000 miles. They have started to realize that in fact they can get away with only changing their oil every 20 – 30,000 miles.
  2. Historically in the US, 80% of the market is in DIY and 20% in DIBSE (Do it by someone else). This has started to shift in favor of DIBSE. Our client has a 2nd position in the DIY market but only a 10th position in the DIBSE market
  3. The CEO of the lubricant business has promised his shareholders a 20% increase in profits over the next 5 years.

What do you suggest we do?

Case Overview

Your client is a car lubricant seller that is experiencing a sudden decline in profits due to changes in the market. In this McKinsey case study, you are being asked to help them understand and address the changing nature of the market by providing concrete strategies for moving forward.

Are you prepping for a first round McKinsey interview? We recommend starting with the Market Study Framework to solve this case, but take it a step further and build your own custom framework to address the specific issue. The most sought after candidates show the ability to take existing frameworks and make them their own.

This case has two math questions and provides an opportunity for case interview math practice. The qualitative difficulty is 2 out of 4, which makes this an intermediate case interview you would see in a McKinsey first round.

McKinsey Interview Tips

What does McKinsey look for in its case interview candidates? Excellent problem-solving and crystal-clear communication skills.

As you work through this case, focus on the following:

  • Come away with 1 key takeaway or area you can improve
  • Time yourself throughout the case -(2min for structure, 5min for math, 2min for brainstorming, 2min for conclusion)

For quality case practice with a pro, book an hour with an ex-MBB interview coach. For more case interview math practice, head back to the Case Library for 500+ practice case studies.

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