Horse Fence

Farmer Finnegan needs to build a fence to keep his horses on his property. He only has a little over 1.5 miles of fence materials, but there’s also a mile-long straight river running through his property. What shape should he use for the fenced in area to give his horses the most space possible?

Our dear friend Finnegan should build a half-circle fence with the river as the diameter, giving the horses about 0.4 square miles to frolic and play in.

Area of semi-circle = πr2 / 2 = π × .5 miles2 / 2 = 0.3927

Posted in Brain Teasers

Give Me Drink and I Die

Feed me and I live, give me drink and I die. What am I?

Fire.

Posted in Riddles

Rooms One Score and Six

This house holds rooms, one score and six,
That shelter a vast mob.
It lets lions lie down with the lambs,
Yet makes both shun the slob.

None now will nestle with nicks and nates,
While reams room near the rear.
Though you and I have separate rooms
Both our bottles brim with beer.

The king and queen can never mate
(Though hands and hearts hobnob)
Because their rooms are separate
If this jail does its job.

What house is this that rules thus
Forcing faith to fend with fear?
The answer to this riddle lies
With dead and dying here.

A dictionary.

Posted in Riddles

The Ages of a Prince and Princess

A princess is as old as the prince will be when the princess is twice the age that the prince was when the princess’s age was half the sum of their present ages.

What are their ages?

This one took a while to figure out and there are numerous valid ways of finding the answer.

Here is the solution I came up with

I created the following table from the riddle:

 CurrentFuturePast
Princessx2z(x+y)/2
Princeyxz

I then created three equations, since the difference in their age will always be the same.
d = the difference in ages
x – y = d
2z – x = d
x/2 + y/2 – z = d

I then created a matrix and solved it using row reduction.

xyz
1-10d
-102d
.5.5-1d

It reduced to:

xyz
1004d
0103d
0015d/2

This means that you can pick any difference you want (an even one presumably because you want integer ages).
Princess age: 4d
Prince age: 3d

Ages that work

PrincessPrince
43
86
1612
2418
3224
4030
4836
5642
6448
7254
8060

To see other solutions check out the comments from when I posted this on my blog.

Posted in Brain Teasers

Remove Four And I’m The Same

I am an English word with five letters. If you remove my last four I am still pronounced the same. What am I?

Queue.

Posted in Riddles

Long and Thin

Long and thin, red within,
With a nail at the end.

What am I?

A finger.

Posted in Riddles

Three Digits in a Row

On a regular 12-hour digital clock how many times would the same three digits in a row be displayed (e.g. 1:11, 11:12, 12:22) in one day?

34 times. These 17 instances will be visible twice in a 24 hour period.

1:11
2:22
3:33
4:44
5:55
10:00
11:10
11:11
11:12
11:13
11:14
11:15
11:16
11:17
11:18
11:19
12:22

Posted in Brain Teasers

Hurt Without Moving

We hurt without moving.
And poison without touching.

We bear truth and lies,
But are not judged by size.

What are we?

Words.

Posted in Riddles
Tagged with

What Does a Cow Have Four Of?

What does a cow have four of, a dog has eight of and you only have two of that can be used standing up or sitting down?

Nipples or teats. Cows have four of them, dogs usually have eight and a human (assuming that’s who’s reading this) has two. Cows milk standing up, dogs often lie down and women usually sit when breastfeeding.

Posted in Riddles

Go in Dry, Come Out Wet

I go in dry and come out wet,
The longer I’m in, the stronger it will get.

What am I?

A tea bag or cement.

Posted in Riddles