Captain Brownbeard’s hourglasses

Captain Brownbeard of the pirateship “The northern star” told his first officer: “Tonight I want to sleep for 7 hours. Wake me exactly 7 hours after I leave the bridge.”

The unfortunate first officer knew that captain Brownbeard had only 1 punishment: eat so many chocolates that you never can stand the sight of chocolate again. He didnt want to suffer such a dreadful fate. To make things worse, he had only two hourglasses, one of 5 hours and one of 3 hours. How can he measure exactly 7 hours? Does he need to make any preparations in advance, and if so, which?

This puzzle is based on a puzzle with hourglasses of 4 and 7 hours which I found in both “More games for the superintelligent,” by James F. Fix and in “Denkspielereien” by Tom Werneck. The same problem can be found on numerous places on the web, with hourglasses of 7 and 11 minutes. This raises of course the question who invented this puzzle, and when?
Oh, by the way, the times used in this puzzle introduce a slight variation.

You can check your solution

Riddles

Some puzzles are more like riddles. Here are some classics:

1) Ox
A farmer in Asia is ploughing his land with a cow. His field is 123 feet long.
With each of its four legs, the cow makes 2 footprints for every feet it walk.
When the farmer walks back along the last straight furrow, how many footprints will he count?

(This one is based on an old problem going back to the middle ages, see the Propositiones by Alcuin of York)

2) Railway crossing
What are the colours on the boom barrier of an uncontrolled railway crossing in Australia?

3) Legal trouble
A plane belonging to a British company with German passengers, crashes on the border between the USA and Canada. In which country will the survivors be buried?

4) More legal stuff
In Belgium, is it legal for a man to merry his widows sister?

Soma cube – part 2

Some time ago I presented some new soma cube puzzles. If you dont know what a soma cube is, have a look here.

Here are 8 new figures:
1) wall

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2) stairs 1

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3) airplane

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4) stairs 2

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5) castle wall 1

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6) gate

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7) castle tower 2

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8) castle tower 3

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If you solved it, we have the solution to
wall,
stairs 1,
airplane,
stairs 2,
castle wall 1,
castle gate,
castle tower 2,
castle tower 3,

Two sons

This weeks puzzle is a simple chance problem. One of my sons has a one out of four chance to win one or perhaps even two medals at skating this weekend. My other son this weekend has a 1 out of 3 chance to win a medal.

What is the chance that at least one of them wins a medal this weekend?

You can check your solution

What comes next?

What comes next in the following sequence?

4 3 3 5 4 4 3 5 5 4 3 ..

If you think you found the solution, you can check the solution

Where does the zero go?

Where does the zero go in this sequence?

8 5 4 9 1 7 6 3 2

I would like to thank fellow consultant Harrie Jans for coming up with this little poser 🙂

If you solved it, we have the solution so you can check yours.

10 Trees in 5 rows

How can you plant 10 trees such that they are planted in 5 rows of 4 trees each?

Three students

Alex is an art-student who sends an email to Bert. Charles is not an art-student. Bert sends an email to Charles.

Now the simple question is: Does an art student send an email to someone who is not an art student?

Yes or No? Or can’t decide because of lack of information?.

This puzzle comes from a presentation by Paul Fenwick, which you can find here

If you solved it, we have the solution so you can check yours.

Pattern code snakes

1) Snakes
What is the code that goes into the question mark?

You can check your solution

Sums with swapped doubles

In this type of puzzle: swap two pairs of digits to make the addition correct. For example, in the illustration above the 7 and the adjacent 0 might have been swapped, or the 3 with one of the 8’s. Your task of course is to restore the original correct sum by finding the two swaps.

1) nr 1^*

1486
3172
—-+
7313

2) nr 2^*
3155
4349
—-+
7317

3) nr 3^*
2748
6146
—-+
6134

4) nr 4^*
9559
1326
—-+
5418

5) nr 5^*
See the illustration at the top of this post.

Nr 3 comes from Issue no 41, 1975, of the famous British magazin Games and Puzzles. I suppose an anonymous editor came up with this puzzle type.
If you have other information about the origin of this puzzle type, I’d love to hear it.

You can find the solutions at 137, 147, 157, 167 and 177

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