Who's lying?

A boy and a girl are talking.

"I am a boy" - said the child with black hair.

"I am a girl" - said the child with white hair.

At least one of them lied. Who is the boy and who is the girl?


Ans:

Both of them are lying! If any one of them is lying, both of them would be either boy of girl which is not as the condition stated at the beginning.

Ultimate Tongue Twisters II

11 Can you can a can as a canner can can a can?

12 Seth at Sainsbury's sells thick socks.

13 You cuss, I cuss, we all cuss, for asparagus! from a Far Side cartoon by Gary Larson

14 Roberta ran rings around the Roman ruins.

15 Clean clams crammed in clean cans.

16 Six sick hicks nick six slick bricks with picks and sticks.

17 I wish to wish the wish you wish to wish, but if you wish the wish the witch wishes, I won't wish the wish you wish to wish.

18 Stupid superstition!

19 There was a fisherman named Fisher who fished for some fish in a fissure. Till a fish with a grin, pulled the fisherman in. Now they're fishing the fissure for Fisher.

20 World Wide Web

Tree and Rope

A rope swing hangs vertically down so that the end is 12 inches above the ground, and 48 inches away from the tree.

If the swing is pulled across so that it touches the tree, it is 20 inches from the ground.

How long is the rope?

Ans:

148 inches.

We can use Pythagoras' theorem if we draw an imaginary line across to create a right-angled triangle.

The hypotenuse is equal to the rope's length R. The bottom of the triangle is 48 inches. The vertical side is R - 8 (the difference between 20 inches and 12 inches).

Pythagoras' theorem tells us that:

   a² + b² = c²

Where c is the hypotenuse.

This gives us:

          48² + (R - 8)² = R²

   2304 + (R - 8)(R - 8) = R²

    2304 + R² - 16R + 64 = R²

         2304 - 16R + 64 = 0

                     16R = 2368

                       R = 148