Jugs with Water

You have a 3 liter jug, a 5 liter jug, and an infinite amount of tap water. How can you measure exactly 4 liters of water using the jugs?

Call the 3 liter jug “small” the 5 liter jug “large”.

  • Fill the large jug with water.
  • Pour 3 liters of water from the large jug into the small jug.
  • Empty the small jug with water.
  • Pour the remaining 2 liters of water from the large jug into the small jug.
  • Fill the large jug with water.
  • Pour water from the large jug into the small jug, until the small jug is full.

Now there are exactly 4 liters of water in the large jug.

A Good Bet

Someone tells you: “I’ll bet you $1 that if you give me $3, I will give you $5 in return”. Is this a good bet?

The bet is not good. If the person gives you the $5, then you would have given him $1+$3=$4, and you would have a profit of $1. However, the person can simply not give you anything and you will lose $5-$1=$4.

A Dream Man at a Funeral

While at her own mother’s funeral, a girl meets a guy she doesn’t know.Β She thinks the guy is amazing – her dream man – and is pretty sure he could be the love of her life. However, she never asks for his name or number and afterwards can not find anyone who knows who he is. A few days later, the girl kills her own sister.

Why did she do it?

The girl assumed the man was a family friend, so she decided he would come also to the funeral of her sister.

Plinks, Plonks, and Plunks

If all plinks are plonks and some plunks are plinks, which of these statements must be true?

  • All plinks are plunks.
  • Some plonks are plunks.
  • Some plinks are not plunks.

Remark: “Some” means more than 0.

The first statement says that the set of plonks contains the set of plinks, and the second statement says that there is at least one plunk-plink. Therefore, that plunk-plink must also be a plonk, and the second statement is true.

The first and the third statements, however, do not need to be true. Indeed, it is possible that there is a plink that is not a plunk, or that all plinks are plunks.

A Dream Last Night

The director of a company wakes up early for a morning flight. He realizes that he forgot some papers at work and goes there. In the office, he meets the night watchman who is leaving for home. The watchman stops the director and tells him that he shouldn’t fly. “I had a dream last night,” the watchman says, “I saw you crash. I saw you die sir, please do not fly today.”

The director listens to the advice of the watchman and decides not to travel. On the next day, the director returns, gives the watchman a generous bonus, and then he fires him. Why?

The plane indeed crashed, so the watchman saved the director’s live. However, apparently, he has been sleeping during his shift, which is the reason the director fires him.