Good Riddles

Answer: If they are round the manhole covers cannot slip into the hole if the hole is slightly smaller than the cover, but if they are square the hole would have to be about 50 percent of the area of the cover to stop the cover from falling into the hole (diagonally).

Answer: He is with the mother.

If you do the math: (baby's age) + 21 + 6 = 5 * (baby's age + 6)
(baby's age) + 27 = 30 + 5 * (baby's age)
-3 = 4 * (baby's age)
-3/4 = baby's age
The baby will be born in 9 months.

Answer: She tells them that she will give the student who skips the quiz whose name comes first alphabetically a detention. This student won't skip because they know they are getting a detention if they do. The next person alphabetically will then know that they will get a detention so they won't skip either, and so on.

Answer: He puts three trees into a triangle then one on a hill in the middle (this forms a tetrahedron).

Answer: A book. Not a pool but it has a cover, not a tree but has leaves, not a slave but is bound, not a website but has pages, and not a shirt but has sleeves.