Brain Teasers 55 - Puzzle Prime

A Maze Puzzle for the Day

Section: Brain Teasers Category: Insight

Difficulty: Hard

Here’s a little maze puzzle I originally built a couple of years ago, that seems apropos to reprise now:

Can you make it from the A in the top left of this grid to the Z in the bottom right, always going either up one letter (for instance, A to B or G to H) or down one letter (for instance, N to M)? The alphabet wraps around, so you can go from Z up to A or A down to Z too. Try as hard as you can (and remember that you can always work backward if you get stuck forwards), and see where you get!

Remark: Solving the maze is not the same thing as solving the puzzle. Read those instructions carefully!

SOLUTION

Notice this puzzle is published on April 1st. Actually, it doesn’t have a standard solution. If you connect every two consecutive letters which appear next to each other in the grid, you will get two disconnected components, one of which contains the START and the other contains the END. The first component has 5 dead-ends – at letters A, P, R, I, L, and the second component has 5 dead-ends – at letters F, O, O, L, S. These two spell out “April Fools”, which is the real solution of the maze.

Steven Stadnicki April 1, 2017

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How Many Letters

Section: Brain Teasers Category: Deduction

Difficulty: Easy

How many letters does the correct answer to this puzzle contain?

SOLUTION

Four – the only number which has the same number of letters as the number itself.

Unknown Author March 22, 2017

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Seven Bridges

Section: Brain Teasers Category: Insight

Difficulty: Advanced

This is a map of old-time Kongsberg. The green shapes are bridges which connect the different parts of the city. Can you find a path through the city which goes through every bridge exactly once?

SOLUTION

No, you cannot. Notice that, except for the first city and the last city section you finish, the number of bridges used in every other section is even. However, there are three sections with an odd number of bridges, and therefore you cannot use all bridges exactly once.

Unknown Author March 19, 2017

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Funky Mate

Section: Brain Teasers Category: Chess

Difficulty: Medium

Place only 2 rooks and 1 knight on the board, so that the Black player is mated.

SOLUTION

You can place the rooks on c5 and e5, and the knight on f5.

Unknown Author March 10, 2017

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Apples or Strawberries

Section: Brain Teasers Category: Insight

Difficulty: Easy

What is heavier – 1 pound of apples or 1 pound of strawberries?

SOLUTION

They are equally heavy – 1 pound each.

Unknown Author March 1, 2017

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Missing Pawns

Section: Brain Teasers Category: Chess

Difficulty: Advanced

White to play and mate in 4 moves.

Remark: The position on the diagram is one which occurs in actual play.

SOLUTION

Notice that the black queen and the black king have switched positions. However, this can happen only if some pawns have been moved. Therefore, we can conclude that the bottom row on the diagram is actually the 8th row of the chessboard. All black and all white pieces have reached their respective opposite sides of the board.

Now, White’s first move is Kb8-d7. The only moves black can play are with the knights. If Black plays Kb1-a3, Kb1-c3 or Kg1-h3, white mates in 2 more moves – Kd7-c5 and Kc5-d3. If Black moves Kg1-f3, then after Kd7-c5 Black can delay the mate by playing Kf3-e5. However, after the white queen takes it with Qxe5, Kc5-d3 is unavoidable.

Unknown Author February 19, 2017

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Marathon

Section: Brain Teasers Category: Insight

Difficulty: Easy

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.

Unknown Author February 16, 2017

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Snail on a Tree

Section: Brain Teasers Category: Insight

Difficulty: Medium

A snail is trying to climb a 10-meter poll. Every day it climbs 4 meters up and then during the night slides 3 meters down. How many days are needed for the snail to get to the top of the poll?

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.

Unknown Author February 4, 2017

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Burn the Ropes

Section: Brain Teasers Category: Insight

Difficulty: Advanced

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.

Unknown Author February 1, 2017

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Running Dog

Section: Brain Teasers Category: Insight

Difficulty: Medium

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.

Unknown Author January 16, 2017

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