Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

When I asked a girl's name she told me her name is the date '07/09/2001'.

I thought for a few seconds and then I got her name. Do you?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

If 1+9+8=1, what is 2+8+9?

Forwards I am heavy, backward I am not. What am I?

John and Jenni are a married couple. They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

I have Rs.50 and I spend it in the way as below.

There was a man he lives in a hotel each morning he presses the first floor button each evening if there is a person in the elevator he asks him to press the 10 floor button if there is no one in the elevator he takes the stairs why.

A girl was standing near the window thinking something. All of a sudden she decides something and throws something out of the window. She dies very soon after throwing it. She was perfectly healthy and had no disease or allergy. No one killed her and she did not commit suicide.

Can you think of any possible explanation that is logical as well for what happened there?

In the picture given below, can you find out which digit will take place of the question mark?