A swan sits at the center of a perfectly circular lake. At an edge of the lake stands a ravenous monster waiting to devour the swan. The monster can not enter the water, but it will run around the circumference of the lake to try to catch the swan as soon as it reaches the shore. The monster moves at 4 times the speed of the swan, and it will always move in the direction along the shore that brings it closer to the swan the quickest. Both the swan and the the monster can change directions in an instant.
The swan knows that if it can reach the lake's shore without the monster right on top of it, it can instantly escape into the surrounding forest.

How can the swan successfully escape?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

If 21x = 79x, what is the value of x?

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?

A man dies of old age on his 25 birthday. How is this possible?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

What has many teeth, but cannot bite?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Can you find the missing piece of the Porsche?