What is the Chance That You’ll Be Correct?

If you choose an answer to this question at random, what is the chance that you will be correct?

a) 25%
b) 50%
c) 60%
d) 25%

This is becomes a self-referential paradox. Both A and D would be correct if there were four unique answers, but since A and D are the same answer, the chance that you would choose a correct answer is 50%, which makes B correct. But if there’s only one correct answer, the odds of choosing the correct one at random goes back to 25%. And around and round you go.

There’s a lot of discussion at Richard Wiseman’s blog and more at Lifehacker, where I first saw this.

Posted in Brain Teasers

Three Lives Have I

Three lives have I.
Gentle enough to soothe the skin,
Light enough to caress the sky,
Hard enough to crack rocks.

Water.

Posted in Riddles

Another 1

What phrase does this represent?

ANOTHER 1
ANOTHER 1
ANOTHER 1
ANOTHER 1
ANOTHER 1

One after another.

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Only Useful When Full

I am only useful when I’m full,
Yet I am always full of holes.

What am I?

A sieve, used for straining food like pasta.

Posted in Riddles

Rhonda At the Ballet

Rhonda will go see ballet but not the opera. Her favorite number is eight and she doesn’t like nine. She likes salmon but not trout. She hates Mondays and likes Wednesdays. Does she use a comb or a brush?

A comb. Rhonda likes words with silent letters, like her name.

Posted in Brain Teasers

Progressive Countdown

If you’re given a number, subtract 1, then 2 from the result, then 3 from that result and so on until you reach 0 or a negative number.

For example, if you’re given 15:

15 – 1 = 14
14 – 2 = 12
12 – 3 = 9
9 – 4 = 5
5 – 5 = 0

Which of these numbers will finish exactly at zero?

102 103 104 105 106

105

105 – 1 = 104
104 – 2 = 102
102 – 3 = 99
99 – 4 = 95
95 – 5 = 90
90 – 6 = 84
84 – 7 = 77
77 – 8 = 69
69 – 9 = 60
60 – 10 = 50
50 – 11 = 39
39 – 12 = 27
27 – 13 = 14
14 – 14 = 0

Posted in Brain Teasers

Apples for Leather

Apples for leather,
leather for silk,
silk for tobacco,
all to get milk.

Bartering.

By Sef Daystrom

Posted in Riddles

Aft to Fore and Fore to Aft

I run fore to aft on one side of a ship and aft to fore on the other. What am I?

The name of the ship.

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Has Teeth But Can’t Bite

What has teeth but can’t bite?

A comb. Other inanimate objects with teeth like a saw, zipper or a gear can “bite” you. Many people can affirm from painful experience in regards to zippers and saws, and the unfortunate factory worker who is missing a finger can attest to gears. It’s a rare event that anyone would be injured by a comb.

Another grim option is a dead animal or person.

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How Many Mangoes?

From a basket of mangoes when counted in twos there was one extra,
counted in threes there were two extra,
counted in fours there were three extra,
counted in fives there were four extra,
counted in sixes there were five extra,
but counted in sevens there were no extras.

At least how many mangoes were there in the basket?

119. The number has to be evenly divisible by seven for there to be no extras when counting in sevens, and it has to be odd in order for there to be one extra when counting by twos. It also can’t be evenly divisible by three through six. 119 is the first odd multiple of 7 that satisfies the requirements.

Posted in Brain Teasers