If it took eight men ten hours to build a wall, how long would it take four men to build it?

Why do we preferably have round manhole covers and not square ones?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den

What is wrong in the below Picture?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

A man was driving a black truck. His lights were not on. The moon was not out. A lady was crossing the street. How did the man see her?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.