Most of the population of the world is concentrated on the continental margins, or more specifically, along the coastlines. This is due to multiple factors, some of which are:
- Climate;
The climate in the coastal regions is usually much more pleasant that the climate deeper into the mainland, so naturally the people preferred to live where it is more pleasant.
- Arable land;
In close proximity to the coastline there's usually nice fertile soil, so it is very suitable for production of food, thus managing to sustain yourself.
- Economy;
The coastal regions, in lots of cases, are well suited for building ports, and that makes them excellent places from where trade can take place, so it strengthens the economy of these places.
Short Answer:
buoyancy
Long answer:
An object submerged in water displaces water according to how much it weighs. In fact, the water will push upward against the object with a force equal to the weight of the water it displaces. For example, a bowling ball and a beach ball that are the same size will have the same volume. The bowling ball, however, is more massive and thus denser than the beach ball. In both cases, the water pushes up against the ball with a force equal to the weight of water it displaced. In the case of the bowling ball, it weighs more than the amount of water it displaced, so it sinks. The beach ball, however, displaces very little water and the air inside it is much lighter than the weight of the water it displaced, so it floats.When lifting something underwater, you have the help of water pushing the object upwards along with your own strength, which is why it's easier to pick up things underwater than on land.
Source:
https://www.wonderopolis.org/wonder/why-is-it-easier-to-lift-someone-in-water-than-on-land
<span>Distance covered by Mario in 6 hours is 330 miles.
Then, Average speed of Mario is 330 miles divided by 6 hours = 55 miles per hour
so to drive a total distance of 715 miles, it would take him ( 715 miles divided by 55 miles per hour) hours
i.e., 13 hours
so Mario will have to drive for 7 more hours to complete a total distance of 715 miles.</span>
The trolleys have been reduced over the last decades, after their initial increase as a public transportation, when new and better ways were discovered/produced for transport, their decline has started.
The buses since their invention, had grown in number and became a very important part of every city's public transportation, and still are.
The rapid transit is the most recent one of the mentioned in here. It's popularity has grown, number increased, and is very practical because it is not causing traffic mess. It is very important transport asset nowadays and makes lives of millions of people much easier.