Five Brilliant Brain Teasers For The Week (27/05/25)

It’s time for another round of clever conundrums to keep your mind sharp and your curiosity piqued. Whether you’re tackling them solo or challenging friends, these five brain teasers range from light warmups to serious head-scratchers. Let’s get started!

🧠 1. The Age Riddle (Easy)

I am two times as old as my sister. In five years, I will be only 1.5 times her age.

How old am I now?

🧠 2. The One-Word Trick (Easy)

What five-letter word becomes shorter when you add two letters to it?

Think literally!

🧩 3. The Light Bulb Puzzle (Medium)

You are in a windowless room with three light switches. Each switch controls one of three light bulbs in the next room. You can turn the switches on and off as much as you like—but you may enter the other room only once.

How can you figure out which switch controls which bulb?

🧩 4. The Poisoned Drink (Medium)

A woman goes to a restaurant and orders an iced tea. She drinks five glasses quickly, while her friend slowly finishes just one. Shortly after, the friend dies from poison in the drink.

How did the woman survive when she drank more?

🧠💥 5. The Prisoner Hat Logic Puzzle (Hard)

Four prisoners are lined up on steps, all facing forward. A wall separates the fourth from the other three. They cannot turn around or move. Each is wearing either a black or white hat.

They do not know what colour hat they're wearing. They are told:

The hats were randomly placed: two black, two white.

They may only speak once to guess their own hat colour.

If any of them guesses incorrectly, they all die.

Only prisoner C (third in line) can see hats in front of them.

D (in the back) can see C, B, and A.

A (front) sees nothing.

Who speaks up, and what do they say to save everyone?

✅ Answers

1. The Age Riddle

Let your age be x and your sister's be y.

Given:

x = 2y

x + 5 = 1.5(y + 5)

Solve:

2y + 5 = 1.5y + 7.5

0.5y = 2.5 → y = 5

So, you are 10 years old.

2. The One-Word Trick

The word is short.

Add "e" and "r" to make shorter.

3. The Light Bulb Puzzle

Turn on the first switch and leave it on for a few minutes.

Turn it off and turn on the second switch.

Go into the other room.

The bulb that’s on = second switch.

The bulb that’s off but warm = first switch.

The bulb that’s off and cold = third switch.

4. The Poisoned Drink

The ice was poisoned, not the tea.

The woman drank quickly—before the ice melted.

The friend drank slowly—allowing the poisoned ice to melt into the drink.

5. The Prisoner Hat Logic Puzzle

Prisoner C speaks.

Here’s how:

D can see C and B. If C and B are wearing the same colour, D knows his must be the opposite—but D says nothing.

So, C realizes that D is silent, which means C and B must be wearing different-coloured hats. Since C can see B’s hat, C knows theirs must be the opposite.

✅ C confidently states their hat colour.

They’re correct, and everyone lives.