EXPLANATION
Computing the ratio of the number of people per unit area:
20/(5 × 5) = 20/25 = 4/5
Now, computing the area occupied by the crowd:
7 feet × 2 miles × 2
2 miles = 10,560 feet
A = 7 feet × 10,560 feet × 2 = 147,840
Therefore, we have the following relationship:
[tex]\frac{Number\text{ of people}}{147840}=\frac{4}{5}[/tex]Isolating the Number of People:
[tex]Number\text{ of People=}\frac{4}{5}*147840[/tex]Multiplying terms:
[tex]Number\text{ of People=118272}[/tex]The answer is 118272 people
