## 100 Offices Riddle

A new medical building containing 100 offices had just been completed. Mark was hired to paint the numbers 1 to 100 on the doors. How many times will Mark have to paint the number nine?

Hint:

Did you say three? The correct answer is twenty (29, 39, and so on).

YES NO

*Did you answer this riddle correctly?*YES NO

## 100 Birds

There was a tree. On the tree there were 100 birds. Then a hunter came he shot a bird from those of them on the tree. How many were left on the tree.

Hint:

## The 1000km Layer

Hint:

## 100 Blank Cards Riddle

Someone offers you the following deal:

There is a deck of 100 initially blank cards. The dealer is allowed to write ANY positive integer, one per card, leaving none blank. You are then asked to turn over as many cards as you wish. If the last card you turn over is the highest in the deck, you win; otherwise, you lose.

Winning grants you $50, and losing costs you only the $10 you paid to play.

Would you accept this challenge?

There is a deck of 100 initially blank cards. The dealer is allowed to write ANY positive integer, one per card, leaving none blank. You are then asked to turn over as many cards as you wish. If the last card you turn over is the highest in the deck, you win; otherwise, you lose.

Winning grants you $50, and losing costs you only the $10 you paid to play.

Would you accept this challenge?

Hint: Perhaps thinking in terms of one deck is the wrong approach.

Yes!

A sample strategy:

Divide the deck in half and turn over all lower 50 cards, setting aside the highest number you find. Then turn over the other 50 cards, one by one, until you reach a number that is higher than the card you set aside: this is your chosen "high card."

Now, there is a 50% chance that the highest card is contained in the top 50 cards (it is or it isn't), and a 50% chance that the second-highest card is contained in the lower 50. Combining the probabilities, you have a 25% chance of constructing the above situation (in which you win every time).

This means that you'll lose three out of four games, but for every four games played, you pay $40 while you win one game and $50. Your net profit every four games is $10.

Obviously, you have to have at least $40 to start in order to apply this strategy effectively.

YES NO

A sample strategy:

Divide the deck in half and turn over all lower 50 cards, setting aside the highest number you find. Then turn over the other 50 cards, one by one, until you reach a number that is higher than the card you set aside: this is your chosen "high card."

Now, there is a 50% chance that the highest card is contained in the top 50 cards (it is or it isn't), and a 50% chance that the second-highest card is contained in the lower 50. Combining the probabilities, you have a 25% chance of constructing the above situation (in which you win every time).

This means that you'll lose three out of four games, but for every four games played, you pay $40 while you win one game and $50. Your net profit every four games is $10.

Obviously, you have to have at least $40 to start in order to apply this strategy effectively.

*Did you answer this riddle correctly?*YES NO

## 10 From 100 Riddle

Hint:

## The Traffic Light Riddle

There is a traffic light at the top of a hill. Cars can't see the light until they are 200 feet from the light.

The cycle of the traffic light is 30 seconds green, 5 seconds yellow and 20 seconds red.

A car is traveling 45 miles per hour up the hill.

What is the probability that the light will be yellow when the driver first crests the hill and that if the driver continues through the intersection at her present speed that she will run a red light?

The cycle of the traffic light is 30 seconds green, 5 seconds yellow and 20 seconds red.

A car is traveling 45 miles per hour up the hill.

What is the probability that the light will be yellow when the driver first crests the hill and that if the driver continues through the intersection at her present speed that she will run a red light?

Hint:

The probability of the driver encountering a yellow light and the light turning red before the car enters the intersection is about 5.5%.

At 45 mph the car is traveling at 66 feet/second and will take just over 3 seconds (3.03) to travel the 200 feet to the intersection. Any yellow light that is in the last 3.03 seconds of the light will cause the driver to run a red light.

The entire cycle of the light is 55 seconds. 3.03/55 = 5.5%.

YES NO

At 45 mph the car is traveling at 66 feet/second and will take just over 3 seconds (3.03) to travel the 200 feet to the intersection. Any yellow light that is in the last 3.03 seconds of the light will cause the driver to run a red light.

The entire cycle of the light is 55 seconds. 3.03/55 = 5.5%.

*Did you answer this riddle correctly?*YES NO

## Noah's Lights Riddle

Hint:

## Light Me Up For A Sprinkle Of Gold Riddle

Hint:

## One Light And Three Switches

This riddle is a favorite among many. No diversions into logical theory or mathematics, just a fun puzzle with a satisfying answer.

There is a lightbulb inside a closet. The door is closed, and you cannot see if the light is on or off through the door. However, you know the light is off to start. Outside of the closet, there are three light switches. One of the switches controls the lightbulb in the closet. You can flip the switches however you want, but once you open the door, you can no longer touch the switches.

How do you figure out without a doubt which switch controls the light?

How do you figure out without a doubt which switch controls the light?

Hint:

Flip switch number 1 and wait a few minutes. Flip switch number 1 back to its original position, and then immediately flip switch number 2.

Open the door. If the light is on, then switch number 2 controls it. If the light is off, then go and feel the bulb with your hand. If the bulb is hot, the switch number 1 controls it, and if the bulb is cold, then switch number 3, the one you did not touch, controls it.

YES NO

Open the door. If the light is on, then switch number 2 controls it. If the light is off, then go and feel the bulb with your hand. If the bulb is hot, the switch number 1 controls it, and if the bulb is cold, then switch number 3, the one you did not touch, controls it.

*Did you answer this riddle correctly?*YES NO

## Who Stole The $100,000 Riddle

A man leaves a $100,000 dollar bill on his desk and leaves work. When he returns the money is gone. He has three suspects: the cook, the cleaning lady, and the mail guy. The cook says he put the money under a book on his desk to keep it safe. They check and it is no longer there. The maid says she moved it when she was cleaning to the inside of the book between page 1 and 2. They open the book and look between page number 1 and 2 but it isn't there. The mail guy says he saw it sticking out of the book and to keep it safe he moved it to between page number 2 and 3. Once they are done the culprit is promptly arrested. Who did it and how did he know?

Hint:

The mail guy did it because if he checked between page numbers 1 and 2 page numbers 2 and 3 are opposite sides of one page and could not hold the dollar bill.

YES NO

*Did you answer this riddle correctly?*YES NO

## A Man Is Sitting In A House At Night That Has No Lights

A man is sitting in a house at night that has no lights on at all. There is no lamp, no candle, nothing. Yet he is reading. How?

Hint:

## Lights On A String

People go round and round me

Adding some lights on a string

And later underneath me

They place the gifts that they bring.

I am a...

Adding some lights on a string

And later underneath me

They place the gifts that they bring.

I am a...

Hint:

## Garland, Lights And Balls Riddle

Hint:

## $100 Bill Grocery Store Thief

A guy walks into a store and steals a $100 bill from the register without the owners knowledge.

He then buys $70 worth of goods using the $100 bill and the owner gives $30 in change.

How much money did the owner lose?

$30, $70, $100, $130, $170, or $200?

He then buys $70 worth of goods using the $100 bill and the owner gives $30 in change.

How much money did the owner lose?

$30, $70, $100, $130, $170, or $200?

Hint:

The best answer from the choices is the owner lost $100. The $100 bill that was stolen was then given back to the owner. What the owner loses is the $70 worth of goods and the $30 in change, which makes for a total of $70 + $30 = $100. The owner has lost $100.

Technically, the owner lost $30 plus the value, V, of the $70 of goods. Since stores typically sell goods at a markup, the value may be less than $70. But in the case of a loss leader, the owner may have lost more than $70.

YES NO

Technically, the owner lost $30 plus the value, V, of the $70 of goods. Since stores typically sell goods at a markup, the value may be less than $70. But in the case of a loss leader, the owner may have lost more than $70.

*Did you answer this riddle correctly?*YES NO

## Steals $100 Riddle

Hint:

## Add Your Riddle Here

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