Complete the table series riddle by finding the number that can replace "??".

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

What does a man do only once in his lifetime, but women do once a year after they are 29?

At a bar, three friends, Mr Green, Mr Red and Mr Blue, were having a drink. One man was wearing a red suit; one a green suit; and the other a blue suit. 'Have you noticed,' said the man in the blue suit, 'that although our suits have colours corresponding to our names, not one of us is wearing a suit that matches our own names?' Mr Red looked at the other two and said, 'You're absolutely correct. What colour suit is each man wearing?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

No matter how little or how much you use me, you change me every month. What am I?

In a box, there is a jumble of 7 red balls, 6 blue balls, 5 green balls, and 4 yellow balls. What is the minimum number of balls, will you have to pick up so that you have at least 4 balls of the same colour?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?