Top 10 Brain Teasers

Ready to challenge your brain? Here’s our collection of brain teasers and the answers! Most people get these wrong. Try now these brain teasers!

1. Red and Blue Balls in a Bag

You have 20 Blue balls and 10 Red balls in a bag. You put your hand in the bag and take off two at a time. If they’re of the same color, you add a Blue ball to the bag. If they’re of different colors, you add a Red ball to the bag. What will be the color of the last ball left in the bag?

2. Handshake Puzzle

At a party, everyone shook hands with everybody else. There were 66 handshakes. How many people were at the party? Some basic ground rules : you don’t shake hands with yourself & you only shake hands once with another person.

3. 10 Coins Puzzle

You are blindfolded and 10 coins are place in front of you on table. You are allowed to touch the coins, but can’t tell which way up they are by feel. You are told that there are 5 coins head up, and 5 coins tails up but not which ones are which. How do you make two piles of coins each with the same number of heads up? You can flip the coins any number of times.

4. Heaven or Hell Puzzle

You are standing before two doors. One of the path leads to heaven and the other one leads to hell. There are two guardians, one by each door. You know one of them always tells the truth and the other always lies, but you don’t know who is the honest one and who is the liar.

You can only ask one question to one of them in order to find the way to heaven. What is the question?

5. River Crossing Puzzle

Sailor Cat needs to bring a wolf, a goat, and a cabbage across the river. The boat is tiny and can only carry one passenger at a time. If he leaves the wolf and the goat alone together, the wolf will eat the goat. If he leaves the goat and the cabbage alone together, the goat will eat the cabbage.
How can he bring all three safely across the river?

6. Defective Ball Puzzle

You are given 8 identical looking balls. One of them is of lighter weight than the rest of the 7 (all the others weigh exactly the same). You a provided with a simple mechanical balance and you are restricted to only 2 uses. Find the heavier ball.

7. 3 Bulbs and Switches Puzzle

You are in a room with 3 switches which correspond to 3 bulbs in another room and you don’t know which switch corresponds to which bulb. You can only enter to the room with the bulbs and back once. You can NOT use any external equipment (power supplies, resistors, etc.). How do you find out which bulb corresponds to which switch?

8. Frog and Well Puzzle

A frog is at the bottom of a 30 meter well. Each day he summons enough energy for one 3 meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

9. Car Wheels Puzzle

A car has 4 tyres and 1 spare tyre. Each tyre can travel a maximum distance of 20000 kilometers before wearing off. What is the maximum distance the car can travel. You are allowed to change tyres (using the spare tyre) unlimited number of times.

10. When is Cheryl’s Birthday?

Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.
May 15 May 16 May 19
June 17 June 18
July 14 July 16
August 14 August 15 August 17

Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.

Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.
Bernard: At first I don’t know when Cheryl’s birthday is, but I know now.
Albert: Then I also know when Cheryl’s birthday is.

So when is Cheryl’s birthday?

One Thought on “Top 10 Brain Teasers

  1. SasiRam on July 19, 2016 at 3:11 pm said:

    Q6.
    i. Place 3 balls on each side of the physical balance, remaining 2 outside. If both sides are equal, then less weight ball must be one of th remainings. So we could check 1 ball on each side and could find out which one has less weight.
    ii. Place 3 balls on each side of the physical balance, remaining 2 outside. If one side has less weight means, then out of that 3 balls one will be less weight. In that three place 1 ball each side of the physical balance and leave the last one outside. If both sides are equal then the one left which is outside is less weighted. If any one of the side is less then it contains the less weight.

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