"locate the missing information, then solve the problem"
11. About 45 000 people could stand on a Canadian football field between the goal posts. How big is the square each person has to stand on?
How big is a Canadian football field between the goal posts?
Since this is not my area of expertise, I searched Google under the key words "canadian football field dimensions" to get this:
http://www.google.com/search?client=safari&rls=en&q=canadian+football+field+dimensions&ie=UTF-8&oe=UTF-8
Divide that by 45,000.
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps.