percent help on sqlzoo

So I am trying to figure out the %population in China compared to the total of the world.
The formula of calculating the percent is: population in china/total population*100

There is also some countries that have not supplied gdp. And my task is to find what continents were all the countries have supplied gdp.

The database is on: http://sqlzoo.net/wiki/SELECT_from_WORLD_Tutorial

Thanks in advice ~WeeDLY

Thread is gone?

No you need to stop modifying it though. Every time you do it'll end up in moderation queue since you are a new member and posting external links.