Spot what is wrong here in below Picture?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

Which word does the below Plexor means ?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.

Can you count the number of quadrilaterals in the picture below?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?