The Age of Three Daughters

I was visiting a friend one evening and remembered that he had three daughters. I asked him how old they were. “The product of their ages is 72,” he answered. Quizzically, I asked, “Is there anything else you can tell me?” “Yes,” he replied, “the sum of their ages is equal to the number of my house.” I stepped outside to see what the house number was. Upon returning inside, I said to my host, “I’m sorry, but I still can’t figure out their ages.” He responded apologetically, “I’m sorry, I forgot to mention that my oldest daughter likes strawberry shortcake.” With this information, I was able to determine all three of their ages. How old is each daughter?

3, 3, and 8. The only groups of 3 factors of 72 to have non-unique sums are “2 6 6” and “3 3 8” (with a sum of 14). The rest have unique sums:

2 + 2 + 18 = 22
2 + 3 + 12 = 18
2 + 4 + 9 = 15
3 + 4 + 6 = 13

The house number alone would have identified any of these groups. Since more information was required, we know the sum left the answer unknown. The presence of a single oldest child eliminates “2 6 6”, leaving “3 3 8” as the only possible answer.

Posted in Brain Teasers

Balance Twelve Eggs

Suppose you have twelve eggs and a balance scale. All of the eggs are identical except for one whose only difference is its weight. Using the scale only three times, determine which egg is the odd egg out and whether it is heavier or lighter than the other eggs.

Weigh four against four. If they’re equal, weigh three of them against three you haven’t weighed. If they balance too, weigh the last remaining egg against any of the others to see if it is lighter or heavier. If the three suspects are heavier, weigh one of them against another and the one that goes down is it. If they balance the remaining suspect is heavy. Use the same process if they’re lighter. If the initial four vs four don’t balance, weigh two heavy eggs and a light egg against one heavy egg, one light one and a known normal egg. If they balance weigh the remaining two light eggs against each other. If they balance the unweighed heavy egg is the odd one out. If the side with two heavy eggs goes down weigh them against each other. If they balance it is the light egg on the other side. If the other side goes down it is either because of one heavy egg on that side or because the one light egg on the other side is lighter than the rest. Weigh one of them against a known normal egg to determine which is true.

Posted in Brain Teasers

One Hundred With Six Identical Digits

How can you express the number 100 using the same digit six times?

99 + 99/99 = 100

Posted in Brain Teasers

I Wave But Never Say Goodbye

I wave my hands at you,
But I never say goodbye.

You’re always cool with me,
Even cooler when I’m high.

What am I?

An electric fan

Posted in Riddles
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If You Break Me

If you break me
I do not stop working,
If you touch me
I may be snared,
If you lose me
Nothing will matter.

What am I?

Hope.

Posted in Riddles

An Eye In A Blue Face

An eye in a blue face
Saw an eye in a green face.
‘That eye is like this eye’
Said the first eye,
But in a low, not high place.

The sun shining on daisies.

Posted in Riddles

I Can Sound a Gong

I’m in bowling and baseball,
For better or for worse,
On a match (but not the sporting kind),
I can sound a gong,
And I’m gone.

What am I?

Strike.

A strike in bowling is good. In baseball it’s good for the pitcher but not for the batter. You can strike a match to light it. When the clock strikes one a gong sounds and when you strike a paragraph, it’s gone.

Posted in Riddles
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Which Door First?

While driving his car a man slams on the brakes when he sees, in the middle of the street, a diamond studded door, a gold door and a silver door. Which door does he open first?

His car door

Posted in Brain Teasers

Rainbow Neighborhood

There was a neighborhood of one-story houses.
One was red and everything in the house was red.
Another was purple and everything in the house was purple.
Yet another was yellow and everything in the house was yellow.
Still another was blue and everything in the house was blue.
In the green house everything was green,
and in the gray house everything was grey.

What color were the stairs in the yellow house?

There are no stairs in any of the houses because they only have one story.

Posted in Brain Teasers

24 from 9, 6, 11 and 3

How do you get 24 from 9, 6, 11 and 3 using addition, subtraction, multiplication or division?

There are multiple solutions.

(6 – 3) × 11 – 9

(11 – 6) × 3 + 9

(9 – 6) × (11 – 3)

Posted in Brain Teasers