Here are the answers to the most difficult engineering interview questions.
Last week, I wrote an article about the most difficult job interview questions from top companies.
So do you have what it takes to be a kickass engineer?
These legit engineering interview questions from top companies make sure they get to hire the best engineers, the cream of the crop.
Such a method screens thousands of applicants easily.
And definitely, these mind-blowing questions will make you think logically and scientifically.
You may need a bit of physics, statistics, and some arithmetic to solve them.
Have you gone nuts already?
Here are the answers from last week’s article.
1. You work on the 60th floor of 100 story building. You walk into your office and find a bomb sitting on your desk. It reads 90 seconds and is counting down. What do you do? – Dropbox
ANSWER #1:
Since there are only 90 seconds left, removing bomb via bottom floor or roof is not possible since there is not enough time. Place bomb in corner of building so that at least half of blast is going out building away from personnel.
2. You are on a game show.
There are three doors, behind one of which is a prize and the other two is a chunk of coal, and the host knows which door holds the prize.
You choose door #1. Before it is opened, the host opens door #3 and reveals a lump of coal.
You have the choice to stick with the door you chose originally or switch to door #2.
What do you do? – Microsoft
ANSWER #2:
Switch doors.
When you chose door #1, there was a 66% chance that the prize was not behind that door.
When the host revealed the coal, there was still a 66% chance the prize was not behind the door you chose.
Thus, you have doubled the odds of getting the prize by switching to door #2.
The key to this puzzle is that the host knew which door has the prize.
”Your choice splits the doors into two sets.”
Set A contains the door you selected, and the probability that is a prize behind this door is 1/3.
The set B contains all remaining doors, and the probability that the winning door is somewhere in there is 2/3.
By removing one door, which all have the success probability of zero because there’s coal behind them, from set B, only one door remains in B, but the overall probability for success in set B is still 2/3.
Therefore you must switch.
3. Pretend 1% of the population has a disease. You have a test that determines if you have that disease, but it’s only 80% accurate and 20% of the time you get a false positive. Your test comes back positive. How likely is it you have the disease? –Google
ANSWER #3:
Fact: 1% of the population has the disease (given)
Data: Test is only 80% accurate, and 20% inaccurate (given):
Assume, Population = 10,000 people
1% have the disease = 100 people
99% do not have the disease = 9,900 people
Of the 1% who have the disease 80% tested +ve = 80
Of the 99% who don’t have the disease 20 tested +ve = 1980
To identify that you have the disease you have to test +ve and actually have the disease = 80 / (80+1980) = 80 / 2060 = 3.88%
4. If you walk 1mile south, 1mile west and 1mile north, you are exactly back where you started. Where are you? –SpaceX, (CEO Elon Musk’s Favorite Question)
ANSWER #4:
There are two answers, North Pole, for common people, and the South Pole, for engineers. Since South Pole presents infinite locations. If you started a mile North of the place where the circumference of the Earth is exactly a mile, then your mile long walk westward circumnavigates the Earth and the walk back takes your where you started. South Pole has circumferences that are 1/nth of a mile giving infinite solutions.
5. Design a spice rack for the blind. –Intel
ANSWER #5:
There are many answers to this but the most practical would be putting braille letters on each label for them to touch.
Using a smelling system may not be safe though, some spices can cause asphyxia.
Another high-tech solution would be integrating electronics where the gadget tells the name of the spice once the button is pressed on a certain container.
6. If you are in a boat in the middle of the pond and drop an anchor, how does the water level vary with respect to shore? – Apple
ANSWER #6:
Water level falls. By definition, the anchor, made of steel, is denser than water. Therefore, its displacement as mass, when it’s on the boat, is greater than its displacement as volume, when it’s in the water. Therefore, if you throw it overboard, the water level falls.
Now you got it like a boss.
