Amazingly, this actually happened. The parents died in a crash crash and their parents fought for the rights to the four frozen embryos left by their late children. After a surrogate pregnancy, the baby was born with DNA matching their deceased parents.

If you answered 1/2, you’re not without comrades, but the generally accepted answer by statisticians (though not without debate) is 1/3. This is because there are four possible combinations: boy-boy, boy-girl, girl-boy and girl-girl. Since we are told one of the children is a boy (but we don’t know if it’s the first or second child), we can rule out the girl-girl combination, leaving three remaining options. Only one out of 3 is boy-boy, so we get a 1/3 chance.

This is a well-known problem known as the Boy or Girl paradox. The other variation is this brain teaser.

57006

The trick is that the word “dead” represents a number in hexadecimal. That number in base 10 is 57005, and adding one more to include yourself gives you: 57005 + 1 = 57006.

An ambulance doesn’t pour water.

Zero. If Fred had correctly labeled four packages, the fifth label would belong to the fifth package and all packages would be correctly labeled. Therefore it is impossible to mislabel exactly four packages.