Last Updated: 21 Nov 2020


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Brain Teaser Questions (the "Microsoft" Questions)

Microsoft has a legendary reputation for asking questions that make candidates think, and you may want to ask the same sorts of questions. Good brain teasers include:

  • You are an airport manager. You need to fit a 1.5 mile runway onto a 1mi square plot of land (1 mi by 1 mi). How do you do it?
  • You are a chef. If you had an infinite supply of water and a 5 quart and 3 quart pail, how would you measure exactly 4 quarts?
  • How many cars/gas stations/piano tuners/etc. are there in the USA?
  • One train leaves Los Angeles at 15mph heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have traveled?
  • You have two jars, 50 red marbles and 50 blue marbles. A jar will be picked at random, and then a marble will be picked from the jar. Placing all of the marbles in the jars, how can you maximize the chances of a red marble being picked? What are the exact odds of getting a red marble using your scheme?
  • You have 4 jars of pills. Each pill is a certain weight, except for contaminated pills contained in one jar, where each pill is weight + 1. How could you tell which jar had the contaminated pills in just one measurement?
  • There are 4 women who want to cross a bridge. They all begin on the same side. You have 17 minutes to get all of them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each woman walks at a different speed. A pair must walk together at the rate of the slower woman's pace.
    • Woman 1: 1 minute to cross
    • Woman 2: 2 minutes to cross
    • Woman 3: 5 minutes to cross
    • Woman 4: 10 minutes to cross
  • For example if Woman 1 and Woman 4 walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Woman 4 then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission. What is the order required to get all women across in 17 minutes? Now, what's the other way?
  • If MS told you we were willing to invest $5 million in a start up of your choice, what business would you start? Why?
  • If you could gather all of the computer manufacturers in the world together into one room and then tell them one thing that they would be compelled to do, what would it be?
  • Explain a scenario for testing a salt shaker.
  • How would you build an alarm clock for deaf people?
  • How would you redesign an ATM?

Additional brain teasers are available on the Microsoft Interview Questions site.


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