I have just had an interview with a well-known consulting firm and experienced for the first time a brain teasing exercise.

Well, under fire, I didn’t find the correct answer. Even if finding the correct answer is always the best thing to do, I am not sure that the goal of those brain teasing exercises is to judge whether you find the correct result or not. In my opinion, it is used to test if the candidate can keep cool and has a brain !

What was asked to me?

How many weddings are performed each year in France?

Statistics show that about 60 000 000 persons live in France.
Assuming that only people between 20 and 30 years old are involved, we can start to apply percentages cuts.
About 10% of the population is between 20 and 30 years old.
As it is asked to give the number of weddings per year, we have to apply another 10% percentage.
10% of 10% later we have 600 000 persons. And of course, if those 600 000 persons are involved in a wedding, you have half of this amount of weddings.
300 000 weddings a year is very close to the statistics given by the National Institute for Statistics and Economic Studies (INSEE)

Another one that I like more but such one I really wouldn’t like to experience lol:

You stand in a room with three light switches. Each controls one
of three light bulbs in the next room. You must figure out which
switch controls which bulb. All lights are off. You have some
limitations— you can flip only two switches and you may enter
the room only once.

One elegant solution is to turn one light bulb on for 10 minutes and turn it off. Turn another bulb on and go into the room. The light bulb that is on clearly goes with the switch that you turned on last. Now feel the bulbs. The hot one was on recently.

See you brain teased people