98560 people
From the given question, we have the following information
The number of people that can fit comfortably in a 5 feet by 5 feet area = 15people
Area = 5ft * 5ft
Area = 25 square feet
The ratio of the number of people per unit area is expressed as:
[tex]\begin{gathered} k=\frac{15}{5\times5} \\ k=\frac{15}{25} \end{gathered}[/tex]Determine the area occupied by the crowd.
[tex]\begin{gathered} Area=7feet×2mile×2 \\ Area=7ft\times10,560ft\times2\text{ \lparen1mile = 5280ft\rparen} \\ Area=147840ft^2 \end{gathered}[/tex]Determine the required size of the crowd
[tex]\begin{gathered} Size\text{ of crowd}=\frac{15}{25}\times147,840 \\ Size\text{ of crowd}=\frac{2}{3}\times147,840 \\ Size\text{ of crowd}=98560peoples \end{gathered}[/tex]Hence the size of a crowd that is standing 7 feet deep on both side of the street along a 2 mile section is 98560 people.