Monty Hall solution

Players initially have a 2/3 chance of picking a goat. Those who swap always get the opposite of their original choice, so those who swap have 2/3 chance of winning the car. Players who stick have a 1/3 chance of winning the car.  The solution is based on the premise that the host knows which door hides the car and intentionally reveals a goat. If the player selected the door hiding the car (1/3), then both remaining doors hide goats and the host may choose either door at random, and switching doors loses in 1/3. On the other hand, if the player initially selected a door that hides a goat (a 2-in-3 chance), then the host’s choice is no longer at random, as he is forced to show the second goat only, and switching doors wins for sure in 2/3.

Post Office Burglary solution

Solution: Derek was the culprit.

Looking at Brian’s statement if it was Charles, then Brian was lying in his first statement, which makes the second statement true. Which would mean that it was both Charles and Alan. So it can’t be Charles.

Which means Derek was lying in his first statement, which makes the second statement true. Therefore it can’t be Alan.

So Eric’s second statement must be false, meaning his first statement was true, therefore it was Derek.

How many triangles solution

The correct answer is 13 triangles – the large outer triangle, plus 9 small inner triangles, plus 3 medium size triangles comprised of 3 triangles each.

Murder mystery solution

Culprit               Weapon           Location
Mrs Red          spanner              kitchen
Dr Purple          rope                     study
Major Yellow     lead piping    library
Miss Beige            gun                   conservatory

Snail racing puzzle solution

# Owner   Wore  Colour
1 Alfred       3     red
2 Alice         2     green
3 Arthur      4     blue
4 Anne         1     yellow

Classical music puzzle solution

Composer        Format     Length
Beethoven      LP album        6
Holst                      single           7
Bach                        CD               8
Butler                     iPod            9

Musical Recital Solution

1 = John played Mozart on the Violin
2 = Nick played Bach on the Piano
3 = Kate played Mozart on the Violin
4 = Mary played Bach on the Violin
5 = Larry played Vivaldi on the Piano

Zebra puzzle solution

There is a solution to this puzzle on Wikipedia.

Crates of Fruit Solution

Take a piece of fruit from the “apples and oranges” crate. If it’s an apple then you know that is the “apples” crate since ALL THE CRATES ARE LABELED INCORRECTLY. This means the crate marked “apples” must be “oranges” and the crate marked “oranges” must be “apples and oranges”.

City of Lies or Truth solution

You ask “In which of those two directions do you live?”

A Citizens of the City of Lies will point to the City of Truth
A Citizens of the City of Truth will point to the City of Truth