Noah, Emma and the Ice Cream Truck

Noah and Emma, track stars with superb hearing, ran as fast as they could to catch up to the ice cream truck in the next town over. They averaged 6 miles per hour, then rested to enjoy their ice cream. They averaged 4 miles per hour over the same distance on the way back. Not counting the time they rested, what was their average speed?

4.8 miles per hour. 5 mph is tempting, but incorrect. Pick any distance, say 12 miles there and 12 miles back. They take two hours to cover the first 12 miles and three hours to cover the return trip. In 5 hours they covered 24 miles which is an overall average of 4.8 miles per hour.

Posted in Brain Teasers

Four Letters and a Fruit or Vegetable

I have four letters in my name,
I am a fruit or a vegetable,
I look like a giant green onion,
I end with the letter k.

What am I?

The leek. It has four letters, has been considered both a fruit and a vegetable, looks like a green onion and ends with the letter k.

Posted in Riddles

Loud Linda

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.

Which is more probable?

1) Linda is a bank teller.
2) Linda is a bank teller and is active in the feminist movement.

1) Linda is a bank teller.

Most people guess number two, but the probability of two events occurring together is always less than or equal to the probability of either one occurring alone. This problem is known as the Conjunction Fallacy.

Posted in Riddles

Three Two Three Sequence

What number belongs at the beginning of this sequence?

?, 3, 2, 3, 9, 2, 4, 8, 4, 3, 7, 6

3 ½.

If you break up the numbers into groups of 4, a,b,c,d, then 2 × |a – d| = |b – c|.

9 2 4 8 → 2 × |9 – 8| = |2 – 4|, or 2 × 1 = 2
4 3 7 6 → 2 × |4 – 6| = |3 – 7|, or 2 × 2 = 4, so
n 3 2 3 → 2 × |3 ½ – 3| = |3 – 2|, or 2 × ½ = 1;

I’m not sure this is the correct solution, but it’s the best I’ve found so far. Email me if you know of a better one.

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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

A Hundred Legs But Can’t Stand

I have a hundred legs, but cannot stand.
I have a long neck, but no head.
I cannot see, yet I help keep your house neat and tidy.

A broom.

Posted in Riddles

Ten Plus Ten Equals Ten

When can ten plus ten equal ten, yet ten minus ten equal twenty?

When putting gloves on then removing them.

Posted in Brain Teasers

Turns Everything Around

What turns everything around but doesn’t move?

A mirror.

Posted in Riddles

A Final Screech

I saw a strange creature,
Long, hard, and straight,
Thrusting in a round, dark, opening,
Preparing to discharge its load of lives,
Puffing and squealing noises accompanied it,
Then a final screech as it slowed and stopped.

Note: This may not be appropriate for younger ages.

A subway train.

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The Secret of the Chalk Emerald

A dear old relative passed away recently and her family gathered for the reading of the will. The final item was the Chalk Emerald, a priceless gem. The will bequeathed it to whoever determined where it was hidden. The only clue was it was in a cylinder surrounded by a thousand squares. A young lass of barely six immediately piped up saying she knew where it was hidden and she was correct. Where was the hiding place?

In a roll of toilet paper.

Mark suggested two alternative solutions: A cylindrical chimney or a well, the squares being the bricks. Although most bricks aren’t square, it’s conceivable I guess.

Posted in Brain Teasers