Can you replace the question mark with the correct number?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

Find the missing number in the sequence.

3 5/3 7/5 11/7 ? 17/11

Three logicians went to bar for having a drink. The bar person asks the logicians "Do they all want to have the drink?". The first logician replied, " I don't know". The second logician replied, " I don't know". What is the reply of the last logician?

What makes this number unique: 8,549,176,320?

Kareena is older than Katrina and younger than Karishma. Isabelle is younger than Bipasha and Karishma. Bipasha is older than Karishma. If Kareena and Isabelle are the same age, who's the youngest?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

Find the missing number: 1, 2, 3, 10, 10, ?, 9,802

In order to complete the racing competition, the Mexico racetrack has to submit its top and the most famous three horses to win the competition. Due to an electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the Mexico racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?