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

Three cars are driving on a track that forms a perfect circle and is wide enough that multiple cars can pass anytime. The car that is leading in the race right now is driving at 55 MPH and the car that is trailing at the last is going at 45 MPH. The car that is in the middle is somewhere between these two speeds.
Right now, you can assume that there is a distance of x miles between the leading car and the middle car and x miles between the middle car and the last car and also, x is not equal to 0 or 1.
The cars maintain their speed till the leading car catches up with the last car and then every car stops. In this scenario, do you think of any point when the distance between any two pairs will again be x miles i.e. the pairs will be x distance apart at the same time ?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

I am the fastest animal but cannot climb the tree. What am I?

Can you decipher the two rows to find the hidden word?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?