I am an odd number. Take away a letter and I become even. What number am I?

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?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

I am green and found in the forest and have needles instead of leaves. What am I?
Hint 1: It can be used for Christmas decorations.
Hint 2: I have a strong, scent that is used in air fresheners.

What is the centre of gravity?

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.

What is it?

You and your two friends are working in a multinational company. How can you three find out the average salary of you all without disclosing your own salary to the other two?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?