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

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

What is the Surname of Barbie Doll?

A word I know,
Six letters contain,
Subtract just one,
And twelve is what remains.

Replace the question mark with the correct number in below Picture:

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

In my garden, I have many trees but only one of them is the mango tree. In these mango trees, there are some mangoes(as expected).

But after a strong wind, there are neither mangoes on the tree nor on the ground. Explain?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)