Interesting logical puzzles for interviews

Good afternoon, Habrovchane!

Interview, especially if you did not pass it :), the thing is not very pleasant. But my dad - a mathematics teacher often said that the exam - is not only a way to assess knowledge, but also the most effective teaching method. It is on the exam (in this case, the interview) that a person is motivated more than ever and his brain works at 100%.

In addition, at the interview they sometimes set up very interesting logical tasks. That's what I want to write about them.
')
So, the most interesting tasks that I was asked at the interview:

Task 1: Pro pool, boat and weight

There is a small pool. In it floats the boat. The current water level is marked on the pool wall.
There is also a cast iron weight. In which case the water level in the pool will rise more: if you lower the weight into the water, or if you lower the weight into the boat?

Task 2: About Bickford Cords

There are two bickfordfire cords and a lighter. Cords may burn unevenly. The only thing known about them is that each of them will burn for exactly one hour. How with the help of these items to detect 45 minutes?

Problem 3: About the rock and rope

Vertical rock 100 meters high. At the top there is a hook for which you can tie a rope. Right under this hook at a height of 50 meters there is a small platform on which you can get up and another hook. At the top of the cliff stands a climber. He has 75 meters of rope and a knife to cut it. How can a mountaineer come down from a cliff? The length of the rope spent on knots is neglected.

Task 4: About the planet and special points

Are there points on planet Earth (if any, where are they) that satisfy the following condition: If you go from a point 100 km to the north, then 100 km to the east, and then 100 km to the south, you will find yourself at the starting point.

I found two of these tasks on the Internet. A little differently formulated.
I did not find two. Maybe bad looking.
Write your answers in comments.
And most importantly, write your interesting puzzles, and links to resources where you can find them.