Marathon
You are running a marathon and right at the finish line, you pass the runner in the 2nd position. In which place do you finish the marathon?
SOLUTION
You finish 2nd. Before passing the runner you were at 3rd place.
Category: Puzzles
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Puzzle Sum 2
What two cities do these sums spell?
SOLUTION
CHIN – N + CAGE – E + O = CHICAGO
ROPE + N – PEN + CHEST + ENGINEER – ENGINE = ROCHESTER
Angry Men
You must go through this maze, avoiding the 16 angry men’s batons. You are allowed to press once each of the four buttons on the walls, which make the men turn clockwise at 90 degrees.
SOLUTION
The solution is shown below.
Snail on a Tree
A snail is trying to climb a
SOLUTION
Seven days only. After the sixth day, the snail would have climbed 6 meters. During the seventh day, it will climb 4 more meters and will get to the top.
Burn the Ropes
You have two ropes and a lighter. Each of the ropes burns out in exactly 60 minutes, but not at a uniform rate – it is possible for example that half of a rope burns out in 40 minutes and the other half in just 20. How can you measure exactly 45 minutes using the ropes and the lighter?
SOLUTION
First, you light up both ends of the first rope and one of the ends of the second rope. Exactly 30 minutes later the first rope will burn out completely and then you have to light up the other end of the second rope. It will take 15 more minutes for the second rope also to burn out completely, for a total of 30 + 15 = 45 minutes.
Puzzle Sum 1
What two animals do these sums spell?
SOLUTION
BABY – Y + MOON – M = BABOON
DON + KEY = DONKEY
Running Dog
Two people – Mick and Goof, 100 meters apart, start walking towards each other with constant speeds of 2m/s. At the same time Mick’s dog starts running back and fourth between them with constant speed of 6m/s until Mick and Goof meet. How much distance does the dog cover in total?
SOLUTION
Mick and Goof will meet after 100/(2 + 2) = 25 seconds. Therefore the dog will run for 25 seconds and will cover 6 x 25 = 150 meters in total.
Missionaries, Cannibals
Three missionaries and three cannibals must cross a river with a boat which can carry at most two people at a time. However, if on one of the two banks of the river the missionaries get outnumbered by the cannibals, they will get eaten. How can all 6 men cross the river without anybody gets eaten?
Remark: The boat cannot cross the river with no people on board.
SOLUTION
Label the missionaries M1, M2, M3 and the cannibals C1, C2, C3. Then:
1. M1 and C1 cross the river, M1 comes back.
2. C2 and C3 cross the river, C2 comes back.
3. M1 and M2 cross the river, M1 and C1 come back.
4. M1 and M3 cross the river, C3 comes back.
5. C1 and C2 cross the river, C1 comes back.
6. C1 and C3 cross the river.
Now, everyone is on the other side.
Friends and Enemies
Show that in each group of 6 people, there are either 3 who know each other, or 3 who do not know each other.
SOLUTION
Let’s call the people A, B, C, D, E, F. Person A either knows at least 3 among B, C, D, E, F, or does not know at least 3 among B, C, D, E, F.
Assume the first possibility – A knows B, C, D. If B and C know each other, C and D know each other, or B and D know each other, then we find a group of 3 people who know each other. Otherwise, B, C, and D form a group in which no-one knows the others.
If A doesn’t know at least 3 among B, C, D, E, F, the arguments are the same.