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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


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.

Tips on answering these questions

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


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?

The Careers Website Glassdoor compiled a list of left-field interview questions. Goldman Sachs asked "How many ping pong balls could you fit into a Jumbo Jet?" and Google asked: "A man pushed his car to a hotel and lost his fortune. What happened?" Lord Grade, the famous media impresario once picked up his water jug and asked the interviewee to "sell it to him". The interviewee thought for a moment, picked up the waste paper bin and set light to it's contents. He then politely asked Lord Grade "Would you like to buy this water jug?" He got the job.

The answer to the Google question by the way is that he was playing Monopoly and apparently you can cram about 31 million ping pong balls into a Jumbo Jet. One clever candidate observed that these would weight about 77,000 Kg. If they were golf balls, they would weigh 1,426,000 Kg - too much for the plane to take off!



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.


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.


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


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)


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


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.


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.


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.


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.

See also


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