Four Chains in One Loop

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

Three cuts. Cut each link in one chain. Separate them, and use the links to join the ends of the three intact chains.

Posted in Brain Teasers

Only Hides in the Unwound

What can be seen but never found that only hides in the unwound?

Relaxation. You can see when someone is relaxing, but no one can remain completely relaxed forever. You can relax more easily as you learn to unwind.

Posted in Riddles

Many and One

They are many and one,
They wave and they drum,
Used to cover a stare,
They go with you everywhere.

Your hands.

Posted in Riddles

At Least One is a Boy

A couple has two children. At least one of them is a boy. Assuming the probability of having a boy or girl is 50%, what is the probability that both children are boys?

If you answered 1/2, you’re not without comrades, but the generally accepted answer by statisticians (though not without debate) is 1/3. This is because there are four possible combinations: boy-boy, boy-girl, girl-boy and girl-girl. Since we are told one of the children is a boy (but we don’t know if it’s the first or second child), we can rule out the girl-girl combination, leaving three remaining options. Only one out of 3 is boy-boy, so we get a 1/3 chance.

This is a well-known problem known as the Boy or Girl paradox. The other variation is this brain teaser.

Posted in Brain Teasers

Made of Ten But Two We Make

Made of ten but two we make,
When assembled others quake,
Five apart and we are weak,
Five together havoc wreak.

What are we?

A fist.

Posted in Riddles

Crawl on the Earth, Rise on Pillar

I crawl on the earth and rise on a pillar.

What am I?

A shadow.

Posted in Riddles

No Head On Which A Hat To Place

I always run but never walk,
I sometimes sing but cannot talk,
No head on which a hat to place,
You always look me in the face.

What am I?

A clock. It runs all the time, it “sings” for hourly chimes, cuckoos or alarms, it doesn’t have a head (but does have hands) and you look a clock in the face to tell the time.

Posted in Riddles

Five Letters But One Left When Two Removed

What word of five letters has only one left when two letters are removed?

Any 5-letter word with the word ‘one’ somewhere in it. Examples include shone, stone, alone, money, loner, phone or ornery. Note it doesn’t say there is only one letter left, but only ‘one’ left. Tricky tricky.

Posted in Riddles

Aiden and Sofia Buying Candy

Aiden and Sofia were debating a major purchase of candy. They calculated that they could get three bags of jelly beans and two bags of chocolate for 24 cents, which was just under their limit of 25 cents. They found they could also get four bags of chocolate and two bags of jelly beans for the same 24 cents. How much did each bag of candy cost?

Jelly beans are 6 cents and chocolate is 3 cents.

Posted in Brain Teasers

Debbie’s Dragster

Debbie starts driving her dragster from rest and constantly accelerates to 60 mph in 10 seconds. How far does she travel in those 10 seconds?

1/12 mile

Ten seconds is 1/6 of a minute and 1 minute is 1/60 of an hour, so 10 seconds is 1/360 of an hour.

If you graph her trip with the speed on the y-axis and the time on the x-axis, you get a triangle with height of 60 mph and width of 1/360 of an hour. To calculate the area of the triangle, you multiply 1/2 × 1/360 × 60 = 1/12.

Posted in Brain Teasers