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1.  When life gives you lemons

Brainteaser: A bloke in a restaurant decides to challenge a waiter. He asks him to bring a glass, plate, water, a match and a lemon wedge. He then proceeds to pour enough water onto the plate to cover it.

"If you, good sir, can get the water into the glass from the plate without touching or moving it, you'll get $100", he challenges the waiter. "You can use all of the items here".

Shortly after the waiter walks away with the cash. What did he do?

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2. Trail by motor bikes

Brainteaser: 

There are 50 motor bikes each with a tank that has the capacity to go 100 km. There are 50 people (one on each motor bike)

The goal is to get one person  to travel as many kilometers as possible. What is the maximum distance that the person can go?

 

3. To break a bulb

Brainteaser: You have two light bulbs in a 100-story building. You want to find the floor at which the bulbs will break when dropped. Find the floor using the least number of drops.

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4. Wasting water

This is a classic one and easily applicable as an example of brainteasers for engineers, let's see if you can figure it out?

Brainteaser: If you had an infinite supply of water and a 5-liter and 3-liter bucket, how would you measure exactly 4 liters? The buckets do not have any intermediate scales.

 

5. Tournament time

Brainteaser: If you had 5,623 participants in a tournament, how many games would need to be played to determine the winner?

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6. Socks, socks everywhere!

Brainteaser: There are 20 different socks of two types in a drawer in a completely dark room. What is the minimum number of socks you should grab to ensure you have a matching pair?

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7. Parking problems

Brainteaser: The probability of finding the parking slot occupied is 1/3. You find it empty for 9 consecutive days. Find the probability that it will be empty on the 10th day.

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8. Losing your marbles

Brainteaser: Imagine that you have three boxes, one containing two black marbles, one containing two white marbles, and the third, one black marble and one white marble. The boxes were labeled for their contents - BB, WW, BW - but someone has switched the labels so that every box is now incorrectly labeled. You are allowed to take one marble at a time out of any box, without looking inside, and by this process of sampling, you are to determine the contents of all three boxes. What is the smallest number of drawings needed to do this?

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9. Plant your flag

Brainteaser: If you have a square room with no roof, and you had four flagpoles you had to plant on the walls so that each flagpole touched two walls, how would you do it?

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10. Weighing things up

Brainteaser: Given 9 balls all of which weigh the same except for one, what is the minimum # of weighings necessary to find the ball that weighs more (or less)? Your only tool is a balance.

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11. Throw it overboard

Brainteaser: You're in a boat and you throw out a suitcase. Does the water level increase?

 

12. The toss of a coin

Brainteaser: You toss two coins. If you get heads with the first coin, you stop. If you get tails, you toss it again. The second coin is tossed regardless. What is the ratio of heads to tails?

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