Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?

There is a box in which distinct numbered balls have been kept. You have to pick two balls randomly from the lot.

If someone is offering you a 2 to 1 odds that the numbers will be relatively prime, for example
If the balls you picked had the numbers 6 and 13, you lose $1.
If the balls you picked had the numbers 5 and 25, you win $2.

Will you accept that bet?

10+10 and 11+11 can give you the same answer.

Explain how?

Can you name some countries which do not have the alphabet 'A' in them?

A train leaves from point A for point B at 80 mph. After half an hour, another train leaves from point B for point A at 60 mph.

Which of the trains will be farther from point A when they meet ?

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Remove two matchsticks to make the below equation correct.

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?