The Lost Dollar

Question: 3 men walk into a hotel. The room they want it is 30 dollars. They each pay ten. Once they get up to their room the manager realizes that the room was only supposed to be 25 dollars. He sends the bellboy up with 5 1 dollar bills. On the way to their room, the belly boy thinks "I can't split five 1s between five guys". So, he pockets 2 of the dollars and gives each of the men a dollar. Now, the men have only paid 9 dollars each. 9X3=27 and the bellboy pocketed 2 dollars which makes 29... Where is the other dollar?

Question: When is 99 more than 100?

Question: How can you make the following true by adding a single line: .9 = 1.

Note: ≠ is not the answer.

Question: There is a 5 gallon and a 3 gallon box. You also have a hose with unlimited water. How are you gonna make the 5 gallon have 4 gallons using your items? (You do not know the exact measure measurements of a gallon)

Question: In a house of Kardak's family each brother have a sisters as double as their brothers and each sister have brothers as same as their sister. How many brothers and sisters in Kardak's family ?

Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?

The glass is a right cylinder.