A maths symbol is hidden in the below Bar Graph. Can you decipher it?

My location can be determined by the below rebus.
So where am i ?

It was a dark stormy night and a couple were in a car driving madly to a city. The car broke down and the husband had to go get help from someone who spoke his language. He was afraid to leave his wife alone in the car so he locked the car before leaving. When he came back, the car was in the same state as he had left it but his wife was dead, there was blood on the floor and there was a stranger in the car. What happened?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

What does this rebus mean?

O
N
C
E
TIME

You have to fill the below given grid in a manner that every row and column contains the digits 1 to 6. Also, make sure that the squares that are connected with each other must contains the same digit.

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

Do You See It?

A mother bought three dress for her triplets daughters(one for each) and put the dresses in the dark. One by one the girls come and pick a dress.
What is the probability that no girl will choose her own dress?