What question can you never answer yes to?

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

If 21x = 79x, what is the value of x?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

I cannot talk, but I always reply when spoken to. What am I?

There was a strange boy who was born before his father. How can this be possible?

Can you solve the photo plexer logic ?

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?