Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

You walk into a creepy house by yourself. There is no electricity, plumbing, or ventilation. Inside you notice 3 doors with numbers on them. Once you open the doors you will die a particular way. Door No.1 You’ll be eaten by a lion who is hungry. Door No.2 You’ll be stabbed to death. Door No.3 There is an electric chair waiting for you. Which door do you pick?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

Identify the 10 differences between the two given pictures.

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?

I always drive my customer away.

Who am I?

What is the fastest way to double your money?