Riddles and Brain Teasers

Different Sizes, Colors and Shapes

What comes in different sizes, colors and shapes but creates a larger whole?

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A jigsaw puzzle piece.

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Around the House Without Touching It

What goes around and in the house, but never touches the house?

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The sun.

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False Positive HIV Test

Imagine an HIV test that is 95% accurate (false positive rate of 5%) and around 2% of the tested population is infected with HIV. What is the probability that you actually have HIV when your test comes back positive?

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29%To read more about this, see the False Positive Paradox page on Wikipedia.

29%

To read more about this, see the False Positive Paradox page on Wikipedia.

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Lucky Number Seven

How is 7 different from the rest of the numbers from 1-10?

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7 (seven) is the only one with two syllables.

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Gain and Lose the Most

Some are quick to take it.
Others must be coaxed.
Those who choose to take it
gain and lose the most.

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Risk.

By Sef Daystrom

Posted in Riddles

Ages Of Myself and My Brother

My current age, is the age of my 14 year-old brother plus one third of my age. How old will I be when my brother is twice his current age?

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I will be 35. I am currently 21.

x = my current age

x = 14 + x/3
3x = 42 + x
2x = 42
x = 21 (so 14 years later, I'll be 35)

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Aunts and Large Families

Dina comes from a large family and has over 20 cousins. How is it possible that all of her cousins have an aunt who is not her aunt?

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The aunt of all of her cousins is Dina’s own mother.

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I Was Not Born

I was not born, but I am here.
I have no name, but I am given many.
I was made by science and life.

What am I?

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A clone.

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Tagged with What am I?

Lives in the Corner

What lives in the corner but travels the world?

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A postage stamp.

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Only Self-Enumerating Number

What is the only self-enumerating number in English?

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Four. The number four has four letters, making it self-enumerating. Interestingly, there are no self-enumerating numbers in French.

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