Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Peter wakes up daily to pick up his cycle and crosses the border between Spain and France daily with a bag on his shoulder. He is investigated daily by the officials but they don't find anything suspicious.

If we tell you that he is smuggling something what would it be?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

Before the start of the car race, John and Jacob have the same amount of fuel in their car. With this fuel, John can drive for 4 hours while Jacob can drive five hours.
After a time they realize that the amount of fuel left in John's car is 1/4th of the fuel in Jacob's.

For how long they are racing?

why number 8549176320 is one of a kind?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

What has a ring but no finger?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Solve the following series:
AZ, GT, MN, __, YB