What does this rebus puzzle means ?

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 ?

10+10 and 11+11 can give you the same answer.

Explain how?

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

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

What has a bottom at the top?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

I inserted a coin in a bottle and closed its mouth with the help of a cork. Now, I was able to take the coin out from the bottle without taking out the cork or breaking the bottle. Can you tell me how I did it?

Can you find the missing piece of the Porsche?