Using Only Five 5's and any mathematical operator make sum as 37

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

What number divided by 4 is the same as that number minus 4?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing.

Why?

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

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?

How do you go from 98 to 720 using just one letter?

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?