You need to arrange three 7 and mathematical symbols to form number 1?

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

What number comes next in this sequence:
7 8 5 5 3 4 4 _

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

Different lights make me strange by changing me into different sizes. What am I?

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

In order to complete the racing competition, the Mexico racetrack has to submit its top and the most famous three horses to win the competition. Due to an electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the Mexico racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?