# CASE INTERVIEWS

A CASE (STUDY)  interview is a type of interview often used for management consulting or investment banking jobs.

Case questions are business problems designed to make you think on your feet. They test your logical and analytical thinking skills, ability to solve problems, structure an answer and use numeracy. Often there are no right answers to these types of questions, but they give the selector an idea of how you think, your temperament and common sense.

Each question may last 20 minutes or more. The interview may last up to an hour of which only half is taken up by case type questions. You may also get logic problems, competency questions, and other standard interview questions

## MARKET SIZING questions

These typically ask you to determine the market size for a particular product. A lot of the skill in answering these questions involved making reasoned estimates of the market size.
• How many women sell AVON products in the UK? (McKinsey)
• How many photocopies are taken in the UK each year? (McKinsey)
• Give the weight of a fully loaded Jumbo Jet at take-off. (LEK)
• How many light bulbs are there in London? (J.P. Morgan)
• How many bottles of beer are drank in the city over the week? (Nielsen)
• If you had 5,623 participants in a tournament, how many games would need to be played to determine the winner? (Amazon)
• Given the numbers 1 to 1000, what is the minimum numbers guesses needed to find a specific number if you are given the hint “higher” or “lower” for each guess you make? (Facebook)
• How do you weigh an elephant without using a weighing machine? (IBM)

### Tips on answering these questions

• Take your time as the problem will be complex and needs careful thought.
• You may be given a pen and paper to takes notes on the question, write down all the key information, make calculations and to brainstorm your ideas and structure your answers.
• Ask questions if necessary: some information may have been left out or you may need to clarify certain points.
• It's fine to use lateral thinking and to be creative with your solutions as long as these also demonstrate common sense.
• Knock the rust off your mental arithmetic and get it back up to speed as you are not usually allowed to use a calculator. Try our numerical aptitude tests  One of the key skills they're after is the ability to structure, both in the interviews and the case studies i.e. the ability to think laterally and make links, and be coherent.
• Make sensible estimates by rounding numbers up or down. For example, even if you know that the population of the United States is 302 million, rounding this to 300 million will make mental calculations much easier and not significantly change the result.
• Consider if your answer makes sense. For example if your answer for the number of women selling Avon products in the UK was 10 million, it would be likely that you had made a fundamental mistake somewhere, so go back and carefully check your working.
• You can use business tools in your answer if appropriate such as a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis or mind mapping
• Commercial awareness can be very important, as questions may be focused round issues faced by the organisation or industry it operates in.

#### How many piano tuners are there in the UK?   (Asked at an LEK interview for management consultancy)

First you need to make common sense estimates about the size of the market.
How many households are there in the UK? (About 25 million).
How many of these have a traditional piano? (You could guess 10%)
How often is a piano tuned? (Say once every year)
How many pianos can a piano tuner tune in a year? Say it takes two hours to tune a piano including travel.
So a tuner could tune perhaps 600 per year. 2.5M/600 = about 4,000 tuners)

To get a more accurate estimate, you could take into account pianos in schools and concert halls and the fact that some piano tuners only work part-time.

## Standard CASE STUDY Questions

#### To perform successfully you may require the ability to:

• Take in information quickly and accurately.
• Analyse problems using logical and critical thinking.
• Identify key issues and prioritise effectively
• Evaluate relevant factors.
• Make rapid, accurate decisions.
• Assess possible problems
• Plan implementation of solutions
• Be aware of resource constraints
• Manage time efficiently
• Have an organised approach
• Work effectively under pressure
• Understand the needs of customers
• Consider implications for the organisation
• Be creative
• How would you approach entering a foreign market with your company? What are the risks what would you need to consider i.e. producing in your home country and importing or producing in the new country and why?
• Advise on whether a company should be restructured or not given a brief about a company in trouble. Asked to identify three main problems and to choose the most important one to tackle first. Relate to Where and how can Accenture help to quickly turn the troubled company around? Give reasons to back up your choice.
• Given some information about a beer company and their falling sales over the last few years. Research had been done to introduce two new beers and had to decide which beer to launch and propose a marketing strategy, whether we wanted to change pricing, product packaging etc.
• A medium sized family run business with 30 shops who had profit problems. How would I turn it around? What services could Accenture sell to the business?, Could the business be saved?
• Discuss all supply chain issues regarding the opening of a flagship Sainsbury's store in London.
• Design an evacuation plan for London. (This is more about finding out how you would approach a problem as there is no single answer here. THrow the ball back into the interviewer's court by asking, 'What type of disaster are we expecting?'. The response for a nuclear attack would be very different from that for a large fire or a terrorist attack.

As in real life there is usually no single correct answer to this type of exercise. Several different solutions could probably be persuasively argued for, and the final solution you choose is not that important. You would be assessed on how logically and eloquently you made your case for whichever scheme you decided to support.

## You may also get LOGIC PROBLEMS:

These questions testing your ability to think quickly and logically and to do quick numeracy under some pressure. See our logic test, numeracy tests and lateral thinking page for some more practice

1. How many degrees are there between clock hands at 3.15? (J.P. Morgan)

2. A sheep farmer has to get to his herd of sheep quickly as he has been told they are being attacked by a dog. His sheep are on the other side of a steep hill. He can run over the hill (2 miles) at 3 miles an hour, or take his tractor via an old dirt track which is 5 miles at an average of 6 miles an hour or he can drive his Land Rover along a very narrow winding road but this is 12 miles and he can only go at 16 miles an hour on average.

Which way should he choose?

3. You spend 21 Euros on meat in a supermarket. You buy a turkey, a chicken and a salmon. The salmon costs half the cost of the turkey and the chicken costs half as much as the salmon. How much did the turkey cost?

4. I spend a third of my money on a guitar, half the rest on a microphone and a quarter of what I then have left on a kazoo. What proportion of my original money do I have left?

5. Why are manhole covers round, not square?

6. In a London Underground tube station there are two up escalators but only one going down. Why?

7. There are three boxes, one contains only apples, one contains only oranges, and one contains both apples and oranges. The boxes have been incorrectly labeled such that no label identifies the actual contents of the box it labels. Opening just one box, and without looking in the box, you take out one piece of fruit. By looking at the fruit, how can you immediately label all of the boxes correctly? (Apple!)

8. You have 8 bags of sugar, 7 weight the same, one weighs less. You also have a balance scale. Find the one that weighs less in less than 3 steps. (Intel)

9. There are 23 football teams playing in a knockout competition. What is the least number of matches they need to play to decide the winner?

#### CLOCK

The answer is not zero degrees as you might at first think. The minute hand will be at 15 minutes (90 degrees clockwise from vertical) but the hour hand will have progressed to one quarter of the distance between 3 pm and 4 pm.

Each hour represents 30 degrees (360 / 12), so one quarter of an hour equals 7.5 degrees, so the minute hand will be at 97.5 degrees: a 7.5 degree difference between the hands.

#### SHEEP FARMER

Running 2 miles at 3 mph takes 40 minutes
Driving the tractor for 5 miles at 6 mph takes 50 minutes
Driving the Land Rover for 12 miles at 16 mph takes 45 minutes
Therefore he should run.

#### SUPERMARKET

Use simple algebra. Say cost of chicken = x, then cost of salmon is 2x and cost of turkey is 4x
Therefore total cost = x + 2x + 4x = 7x
7x = 21 Euros
Therefore x = 3 Euros
Turkey costs 4x which is 12 Euros

#### MUSICAL INSTRUMENTS

After spending one third of my money on the guitar I have two thirds left. I spend half of this on a microphone, so this is again one third. I then have one third of my original money remaining. I spend one quarter of this on the kazoo. One quarter of one third is one twelfth. I thus have three quarters of one third of my money remaining. Three quarters of one third is one quarter remaining. (1/3 = 4/12.   4/12 - 1/12 = 3/12.  3/12 = 1/4)

#### MANHOLE COVER

Round covers can never be dropped down the hole, but square ones can if you turn them diagonally to the hole.

#### LONDON UNDERGROUND

People leave trains packed in a group, so arrive at the escalators at the same time, but tend to go down to the trains in a more even stream.

#### THREE BOXES

Open the box that is labeled "Apples and Oranges".
You know that since none of the labels are correct, the box must either contain only apples, or only oranges.
Suppose that you remove an apple from that box. Therefore, that box must be the "Apples Only" box.

One of the two remaining boxes must be the "Oranges Only" box. However, one is labeled "Apples Only", and the other is labeled "Oranges Only". Therefore, the one labeled "Apples Only" is the box that contains only oranges, and the box labeled "Oranges Only" is the box that contains both kinds of fruit.

#### BAGS OF SUGAR

Put 2 bags to the side. Weight 3 of the remaining bags against the other 3 remaining. If they weigh the same then weigh the 2 bags that you put aside to find out which of them is heavier. If, however, one of the sets of 3 bags was heavier, put one of the bags from the heavier set aside. Weigh the remaining two bags from the set to find out which one is heavier. If they are equal then you know that it is the 1 bag that you put aside.

#### FOOTBALL

in a knockout competition, every team except the winner is defeated once and once only, so the number of matches is one less than the number of teams in this case 23-1 = 22.