Logic Lesson 2018











You are a prisoner in a room with 2 doors and 2 guards. One of the doors will guide you to freedom and behind the other is a hangman –you don’t know which is which.

One of the guards always tells the truth and the other always lies. You don’t know which one is the truth-teller or the liar either.

You have to choose and open one of these doors, but you can only ask a single question to one of the guards.

What do you ask so you can pick the door to freedom?

Car Park



The Most Intelligent Prince

A king wants his daughter to marry the smartest of 3 extremely intelligent young princes, and so the king’s wise men devised an intelligence test.

The princes are gathered into a room and seated, facing one another, and are shown 2 black hats and 3 white hats. They are blindfolded, and 1 hat is placed on each of their heads, with the remaining hats hidden in a different room.

The king tells them that the first prince to deduce the color of his hat without removing it or looking at it will marry his daughter. A wrong guess will mean death. The blindfolds are then removed.

You are one of the princes. You see 2 white hats on the other prince’s heads. After some time you realize that the other prince’s are unable to deduce the color of their hat, or are unwilling to guess. What color is your hat?

Note: You know that your competitors are very intelligent and want nothing more than to marry the princess. You also know that the king is a man of his word, and he has said that the test is a fair test of intelligence and bravery.


The 100 Coins

There are 10 sets of 10 coins. You know how much the coins should weigh. You know all the coins in one set of ten are exactly a hundredth of an ounce off, making the entire set of ten coins a tenth of an ounce off. You also know that all the other coins weight the correct amount. You are allowed to use an extremely accurate digital weighing machine only once.

How do you determine which set of 10 coins is faulty?


Dracula is locked in one of three caskets.
One is solid red, one is solid yellow, one is solid blue.
The caskets have inscriptions:
Red says, Dracula is here (meaning inside the casket)
Yellow says, Dracula is not here (not inside the casket)
Blue says, Dracula is not in the red casket

Only one inscription is true.

Where must Dracula be?



The questions

1. How many tourists are staying at this camp?

2. When did they arrive: today or a few days ago?

3. How did they get here?

4. How far away is the closest town?

5. Where does the wind blow: from the north or from the south?

6. What time of day is it?

7. Where did Alex go?

8. Who was on duty yesterday? (Give their name)

9. What day is it today?

The answers

1. There are four tourists. See the four sets of cutlery on the picnic blanket and four names on the duty list.

2. They arrived a few days ago – long enough for a spider to build a web between their tent and a tree.

3. They got there by boat, judging be the oars next to the tree.

4. The closest village is not far – the chicken wouldn’t be walking around in the area otherwise

5. The wind is blowing from the south. The flag on top of the tent shows the wind direction and, looking at the trees, branches on the southern side are normally longer.

6. It’s morning. The shadows show the sun is to their east.

7. Alex is catching butterflies – see the scoop net behind the tent.

8. Colin was on duty yesterday. He’s looking for something in his backpack, which is marked with a “C”. Alex is catching butterflies. James is taking pictures. Peter is on duty today, and Colin was on duty yesterday.

9. It’s August 8th – because Peter is on duty and there is a watermelon on the ground. Watermelons ripen in August. Apparently.

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